text: /*
   *  libata-eh.c - libata error handling
   *
   *  Maintained by:  Jeff Garzik <jgarzik@pobox.com>
   *    		    Please ALWAYS copy linux-ide@vger.kernel.org
   *		    on emails.
   *
   *  Copyright 2006 Tejun Heo <htejun@gmail.com>
   *
   *
   *  This program is free software; you can redistribute it and/or
   *  modify it under the terms of the GNU General Public License as
   *  published by the Free Software Foundation; either version 2, or
   *  (at your option) any later version.
   *
   *  This program is distributed in the hope that it will be useful,
   *  but WITHOUT ANY WARRANTY; without even the implied warranty of
   *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   *  General Public License for more details.
   *
   *  You should have received a copy of the GNU General Public License
   *  along with this program; see the file COPYING.  If not, write to
   *  the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139,
   *  USA.
   *
   *
   *  libata documentation is available via 'make {ps|pdf}docs',
   *  as Documentation/DocBook/libata.*
   *
   *  Hardware documentation available from http://www.t13.org/ and
   *  http://www.sata-io.org/
   *
   */
  
  #include <linux/kernel.h>
  #include <linux/blkdev.h>
  #include <linux/export.h>
  #include <linux/pci.h>
  #include <scsi/scsi.h>
  #include <scsi/scsi_host.h>
  #include <scsi/scsi_eh.h>
  #include <scsi/scsi_device.h>
  #include <scsi/scsi_cmnd.h>
  #include <scsi/scsi_dbg.h>
  #include "../scsi/scsi_transport_api.h"
  
  #include <linux/libata.h>
  
  #include "libata.h"
  
  enum {
  	/* speed down verdicts */
  	ATA_EH_SPDN_NCQ_OFF		= (1 << 0),
  	ATA_EH_SPDN_SPEED_DOWN		= (1 << 1),
  	ATA_EH_SPDN_FALLBACK_TO_PIO	= (1 << 2),
  	ATA_EH_SPDN_KEEP_ERRORS		= (1 << 3),
  
  	/* error flags */
  	ATA_EFLAG_IS_IO			= (1 << 0),
  	ATA_EFLAG_DUBIOUS_XFER		= (1 << 1),
  	ATA_EFLAG_OLD_ER                = (1 << 31),
  
  	/* error categories */
  	ATA_ECAT_NONE			= 0,
  	ATA_ECAT_ATA_BUS		= 1,
  	ATA_ECAT_TOUT_HSM		= 2,
  	ATA_ECAT_UNK_DEV		= 3,
  	ATA_ECAT_DUBIOUS_NONE		= 4,
  	ATA_ECAT_DUBIOUS_ATA_BUS	= 5,
  	ATA_ECAT_DUBIOUS_TOUT_HSM	= 6,
  	ATA_ECAT_DUBIOUS_UNK_DEV	= 7,
  	ATA_ECAT_NR			= 8,
  
  	ATA_EH_CMD_DFL_TIMEOUT		=  5000,
  
  	/* always put at least this amount of time between resets */
  	ATA_EH_RESET_COOL_DOWN		=  5000,
  
  	/* Waiting in ->prereset can never be reliable.  It's
  	 * sometimes nice to wait there but it can't be depended upon;
  	 * otherwise, we wouldn't be resetting.  Just give it enough
  	 * time for most drives to spin up.
  	 */
  	ATA_EH_PRERESET_TIMEOUT		= 10000,
  	ATA_EH_FASTDRAIN_INTERVAL	=  3000,
  
  	ATA_EH_UA_TRIES			= 5,
  
  	/* probe speed down parameters, see ata_eh_schedule_probe() */
  	ATA_EH_PROBE_TRIAL_INTERVAL	= 60000,	/* 1 min */
  	ATA_EH_PROBE_TRIALS		= 2,
  };
  
  /* The following table determines how we sequence resets.  Each entry
   * represents timeout for that try.  The first try can be soft or
   * hardreset.  All others are hardreset if available.  In most cases
   * the first reset w/ 10sec timeout should succeed.  Following entries
   * are mostly for error handling, hotplug and retarded devices.
   */
  static const unsigned long ata_eh_reset_timeouts[] = {
  	10000,	/* most drives spin up by 10sec */
  	10000,	/* > 99% working drives spin up before 20sec */
  	35000,	/* give > 30 secs of idleness for retarded devices */
  	 5000,	/* and sweet one last chance */
  	ULONG_MAX, /* > 1 min has elapsed, give up */
  };
  
  static const unsigned long ata_eh_identify_timeouts[] = {
  	 5000,	/* covers > 99% of successes and not too boring on failures */
  	10000,  /* combined time till here is enough even for media access */
  	30000,	/* for true idiots */
  	ULONG_MAX,
  };
  
  static const unsigned long ata_eh_flush_timeouts[] = {
  	15000,	/* be generous with flush */
  	15000,  /* ditto */
  	30000,	/* and even more generous */
  	ULONG_MAX,
  };
  
  static const unsigned long ata_eh_other_timeouts[] = {
  	 5000,	/* same rationale as identify timeout */
  	10000,	/* ditto */
  	/* but no merciful 30sec for other commands, it just isn't worth it */
  	ULONG_MAX,
  };
  
  struct ata_eh_cmd_timeout_ent {
  	const u8		*commands;
  	const unsigned long	*timeouts;
  };
  
  /* The following table determines timeouts to use for EH internal
   * commands.  Each table entry is a command class and matches the
   * commands the entry applies to and the timeout table to use.
   *
   * On the retry after a command timed out, the next timeout value from
   * the table is used.  If the table doesn't contain further entries,
   * the last value is used.
   *
   * ehc->cmd_timeout_idx keeps track of which timeout to use per
   * command class, so if SET_FEATURES times out on the first try, the
   * next try will use the second timeout value only for that class.
   */
  #define CMDS(cmds...)	(const u8 []){ cmds, 0 }
  static const struct ata_eh_cmd_timeout_ent
  ata_eh_cmd_timeout_table[ATA_EH_CMD_TIMEOUT_TABLE_SIZE] = {
  	{ .commands = CMDS(ATA_CMD_ID_ATA, ATA_CMD_ID_ATAPI),
  	  .timeouts = ata_eh_identify_timeouts, },
  	{ .commands = CMDS(ATA_CMD_READ_NATIVE_MAX, ATA_CMD_READ_NATIVE_MAX_EXT),
  	  .timeouts = ata_eh_other_timeouts, },
  	{ .commands = CMDS(ATA_CMD_SET_MAX, ATA_CMD_SET_MAX_EXT),
  	  .timeouts = ata_eh_other_timeouts, },
  	{ .commands = CMDS(ATA_CMD_SET_FEATURES),
  	  .timeouts = ata_eh_other_timeouts, },
  	{ .commands = CMDS(ATA_CMD_INIT_DEV_PARAMS),
  	  .timeouts = ata_eh_other_timeouts, },
  	{ .commands = CMDS(ATA_CMD_FLUSH, ATA_CMD_FLUSH_EXT),
  	  .timeouts = ata_eh_flush_timeouts },
  };
  #undef CMDS
  
  static void __ata_port_freeze(struct ata_port *ap);
  #ifdef CONFIG_PM
  static void ata_eh_handle_port_suspend(struct ata_port *ap);
  static void ata_eh_handle_port_resume(struct ata_port *ap);
  #else /* CONFIG_PM */
  static void ata_eh_handle_port_suspend(struct ata_port *ap)
  { }
  
  static void ata_eh_handle_port_resume(struct ata_port *ap)
  { }
  #endif /* CONFIG_PM */
  
  static void __ata_ehi_pushv_desc(struct ata_eh_info *ehi, const char *fmt,
  				 va_list args)
  {
  	ehi->desc_len += vscnprintf(ehi->desc + ehi->desc_len,
  				     ATA_EH_DESC_LEN - ehi->desc_len,
  				     fmt, args);
  }
  
  /**
   *	__ata_ehi_push_desc - push error description without adding separator
   *	@ehi: target EHI
   *	@fmt: printf format string
   *
   *	Format string according to @fmt and append it to @ehi->desc.
   *
   *	LOCKING:
   *	spin_lock_irqsave(host lock)
   */
  void __ata_ehi_push_desc(struct ata_eh_info *ehi, const char *fmt, ...)
  {
  	va_list args;
  
  	va_start(args, fmt);
  	__ata_ehi_pushv_desc(ehi, fmt, args);
  	va_end(args);
  }
  
  /**
   *	ata_ehi_push_desc - push error description with separator
   *	@ehi: target EHI
   *	@fmt: printf format string
   *
   *	Format string according to @fmt and append it to @ehi->desc.
   *	If @ehi->desc is not empty, ", " is added in-between.
   *
   *	LOCKING:
   *	spin_lock_irqsave(host lock)
   */
  void ata_ehi_push_desc(struct ata_eh_info *ehi, const char *fmt, ...)
  {
  	va_list args;
  
  	if (ehi->desc_len)
  		__ata_ehi_push_desc(ehi, ", ");
  
  	va_start(args, fmt);
  	__ata_ehi_pushv_desc(ehi, fmt, args);
  	va_end(args);
  }
  
  /**
   *	ata_ehi_clear_desc - clean error description
   *	@ehi: target EHI
   *
   *	Clear @ehi->desc.
   *
   *	LOCKING:
   *	spin_lock_irqsave(host lock)
   */
  void ata_ehi_clear_desc(struct ata_eh_info *ehi)
  {
  	ehi->desc[0] = '\0';
  	ehi->desc_len = 0;
  }
  
  /**
   *	ata_port_desc - append port description
   *	@ap: target ATA port
   *	@fmt: printf format string
   *
   *	Format string according to @fmt and append it to port
   *	description.  If port description is not empty, " " is added
   *	in-between.  This function is to be used while initializing
   *	ata_host.  The description is printed on host registration.
   *
   *	LOCKING:
   *	None.
   */
  void ata_port_desc(struct ata_port *ap, const char *fmt, ...)
  {
  	va_list args;
  
  	WARN_ON(!(ap->pflags & ATA_PFLAG_INITIALIZING));
  
  	if (ap->link.eh_info.desc_len)
  		__ata_ehi_push_desc(&ap->link.eh_info, " ");
  
  	va_start(args, fmt);
  	__ata_ehi_pushv_desc(&ap->link.eh_info, fmt, args);
  	va_end(args);
  }
  
  #ifdef CONFIG_PCI
  
  /**
   *	ata_port_pbar_desc - append PCI BAR description
   *	@ap: target ATA port
   *	@bar: target PCI BAR
   *	@offset: offset into PCI BAR
   *	@name: name of the area
   *
   *	If @offset is negative, this function formats a string which
   *	contains the name, address, size and type of the BAR and
   *	appends it to the port description.  If @offset is zero or
   *	positive, only name and offsetted address is appended.
   *
   *	LOCKING:
   *	None.
   */
  void ata_port_pbar_desc(struct ata_port *ap, int bar, ssize_t offset,
  			const char *name)
  {
  	struct pci_dev *pdev = to_pci_dev(ap->host->dev);
  	char *type = "";
  	unsigned long long start, len;
  
  	if (pci_resource_flags(pdev, bar) & IORESOURCE_MEM)
  		type = "m";
  	else if (pci_resource_flags(pdev, bar) & IORESOURCE_IO)
  		type = "i";
  
  	start = (unsigned long long)pci_resource_start(pdev, bar);
  	len = (unsigned long long)pci_resource_len(pdev, bar);
  
  	if (offset < 0)
  		ata_port_desc(ap, "%s %s%llu@0x%llx", name, type, len, start);
  	else
  		ata_port_desc(ap, "%s 0x%llx", name,
  				start + (unsigned long long)offset);
  }
  
  #endif /* CONFIG_PCI */
  
  static int ata_lookup_timeout_table(u8 cmd)
  {
  	int i;
  
  	for (i = 0; i < ATA_EH_CMD_TIMEOUT_TABLE_SIZE; i++) {
  		const u8 *cur;
  
  		for (cur = ata_eh_cmd_timeout_table[i].commands; *cur; cur++)
  			if (*cur == cmd)
  				return i;
  	}
  
  	return -1;
  }
  
  /**
   *	ata_internal_cmd_timeout - determine timeout for an internal command
   *	@dev: target device
   *	@cmd: internal command to be issued
   *
   *	Determine timeout for internal command @cmd for @dev.
   *
   *	LOCKING:
   *	EH context.
   *
   *	RETURNS:
   *	Determined timeout.
   */
  unsigned long ata_internal_cmd_timeout(struct ata_device *dev, u8 cmd)
  {
  	struct ata_eh_context *ehc = &dev->link->eh_context;
  	int ent = ata_lookup_timeout_table(cmd);
  	int idx;
  
  	if (ent < 0)
  		return ATA_EH_CMD_DFL_TIMEOUT;
  
  	idx = ehc->cmd_timeout_idx[dev->devno][ent];
  	return ata_eh_cmd_timeout_table[ent].timeouts[idx];
  }
  
  /**
   *	ata_internal_cmd_timed_out - notification for internal command timeout
   *	@dev: target device
   *	@cmd: internal command which timed out
   *
   *	Notify EH that internal command @cmd for @dev timed out.  This
   *	function should be called only for commands whose timeouts are
   *	determined using ata_internal_cmd_timeout().
   *
   *	LOCKING:
   *	EH context.
   */
  void ata_internal_cmd_timed_out(struct ata_device *dev, u8 cmd)
  {
  	struct ata_eh_context *ehc = &dev->link->eh_context;
  	int ent = ata_lookup_timeout_table(cmd);
  	int idx;
  
  	if (ent < 0)
  		return;
  
  	idx = ehc->cmd_timeout_idx[dev->devno][ent];
  	if (ata_eh_cmd_timeout_table[ent].timeouts[idx + 1] != ULONG_MAX)
  		ehc->cmd_timeout_idx[dev->devno][ent]++;
  }
  
  static void ata_ering_record(struct ata_ering *ering, unsigned int eflags,
  			     unsigned int err_mask)
  {
  	struct ata_ering_entry *ent;
  
  	WARN_ON(!err_mask);
  
  	ering->cursor++;
  	ering->cursor %= ATA_ERING_SIZE;
  
  	ent = &ering->ring[ering->cursor];
  	ent->eflags = eflags;
  	ent->err_mask = err_mask;
  	ent->timestamp = get_jiffies_64();
  }
  
  static struct ata_ering_entry *ata_ering_top(struct ata_ering *ering)
  {
  	struct ata_ering_entry *ent = &ering->ring[ering->cursor];
  
  	if (ent->err_mask)
  		return ent;
  	return NULL;
  }
  
  int ata_ering_map(struct ata_ering *ering,
  		  int (*map_fn)(struct ata_ering_entry *, void *),
  		  void *arg)
  {
  	int idx, rc = 0;
  	struct ata_ering_entry *ent;
  
  	idx = ering->cursor;
  	do {
  		ent = &ering->ring[idx];
  		if (!ent->err_mask)
  			break;
  		rc = map_fn(ent, arg);
  		if (rc)
  			break;
  		idx = (idx - 1 + ATA_ERING_SIZE) % ATA_ERING_SIZE;
  	} while (idx != ering->cursor);
  
  	return rc;
  }
  
  int ata_ering_clear_cb(struct ata_ering_entry *ent, void *void_arg)
  {
  	ent->eflags |= ATA_EFLAG_OLD_ER;
  	return 0;
  }
  
  static void ata_ering_clear(struct ata_ering *ering)
  {
  	ata_ering_map(ering, ata_ering_clear_cb, NULL);
  }
  
  static unsigned int ata_eh_dev_action(struct ata_device *dev)
  {
  	struct ata_eh_context *ehc = &dev->link->eh_context;
  
  	return ehc->i.action | ehc->i.dev_action[dev->devno];
  }
  
  static void ata_eh_clear_action(struct ata_link *link, struct ata_device *dev,
  				struct ata_eh_info *ehi, unsigned int action)
  {
  	struct ata_device *tdev;
  
  	if (!dev) {
  		ehi->action &= ~action;
  		ata_for_each_dev(tdev, link, ALL)
  			ehi->dev_action[tdev->devno] &= ~action;
  	} else {
  		/* doesn't make sense for port-wide EH actions */
  		WARN_ON(!(action & ATA_EH_PERDEV_MASK));
  
  		/* break ehi->action into ehi->dev_action */
  		if (ehi->action & action) {
  			ata_for_each_dev(tdev, link, ALL)
  				ehi->dev_action[tdev->devno] |=
  					ehi->action & action;
  			ehi->action &= ~action;
  		}
  
  		/* turn off the specified per-dev action */
  		ehi->dev_action[dev->devno] &= ~action;
  	}
  }
  
  /**
   *	ata_eh_acquire - acquire EH ownership
   *	@ap: ATA port to acquire EH ownership for
   *
   *	Acquire EH ownership for @ap.  This is the basic exclusion
   *	mechanism for ports sharing a host.  Only one port hanging off
   *	the same host can claim the ownership of EH.
   *
   *	LOCKING:
   *	EH context.
   */
  void ata_eh_acquire(struct ata_port *ap)
  {
  	mutex_lock(&ap->host->eh_mutex);
  	WARN_ON_ONCE(ap->host->eh_owner);
  	ap->host->eh_owner = current;
  }
  
  /**
   *	ata_eh_release - release EH ownership
   *	@ap: ATA port to release EH ownership for
   *
   *	Release EH ownership for @ap if the caller.  The caller must
   *	have acquired EH ownership using ata_eh_acquire() previously.
   *
   *	LOCKING:
   *	EH context.
   */
  void ata_eh_release(struct ata_port *ap)
  {
  	WARN_ON_ONCE(ap->host->eh_owner != current);
  	ap->host->eh_owner = NULL;
  	mutex_unlock(&ap->host->eh_mutex);
  }
  
  /**
   *	ata_scsi_timed_out - SCSI layer time out callback
   *	@cmd: timed out SCSI command
   *
   *	Handles SCSI layer timeout.  We race with normal completion of
   *	the qc for @cmd.  If the qc is already gone, we lose and let
   *	the scsi command finish (EH_HANDLED).  Otherwise, the qc has
   *	timed out and EH should be invoked.  Prevent ata_qc_complete()
   *	from finishing it by setting EH_SCHEDULED and return
   *	EH_NOT_HANDLED.
   *
   *	TODO: kill this function once old EH is gone.
   *
   *	LOCKING:
   *	Called from timer context
   *
   *	RETURNS:
   *	EH_HANDLED or EH_NOT_HANDLED
   */
  enum blk_eh_timer_return ata_scsi_timed_out(struct scsi_cmnd *cmd)
  {
  	struct Scsi_Host *host = cmd->device->host;
  	struct ata_port *ap = ata_shost_to_port(host);
  	unsigned long flags;
  	struct ata_queued_cmd *qc;
  	enum blk_eh_timer_return ret;
  
  	DPRINTK("ENTER\n");
  
  	if (ap->ops->error_handler) {
  		ret = BLK_EH_NOT_HANDLED;
  		goto out;
  	}
  
  	ret = BLK_EH_HANDLED;
  	spin_lock_irqsave(ap->lock, flags);
  	qc = ata_qc_from_tag(ap, ap->link.active_tag);
  	if (qc) {
  		WARN_ON(qc->scsicmd != cmd);
  		qc->flags |= ATA_QCFLAG_EH_SCHEDULED;
  		qc->err_mask |= AC_ERR_TIMEOUT;
  		ret = BLK_EH_NOT_HANDLED;
  	}
  	spin_unlock_irqrestore(ap->lock, flags);
  
   out:
  	DPRINTK("EXIT, ret=%d\n", ret);
  	return ret;
  }
  
  static void ata_eh_unload(struct ata_port *ap)
  {
  	struct ata_link *link;
  	struct ata_device *dev;
  	unsigned long flags;
  
  	/* Restore SControl IPM and SPD for the next driver and
  	 * disable attached devices.
  	 */
  	ata_for_each_link(link, ap, PMP_FIRST) {
  		sata_scr_write(link, SCR_CONTROL, link->saved_scontrol & 0xff0);
  		ata_for_each_dev(dev, link, ALL)
  			ata_dev_disable(dev);
  	}
  
  	/* freeze and set UNLOADED */
  	spin_lock_irqsave(ap->lock, flags);
  
  	ata_port_freeze(ap);			/* won't be thawed */
  	ap->pflags &= ~ATA_PFLAG_EH_PENDING;	/* clear pending from freeze */
  	ap->pflags |= ATA_PFLAG_UNLOADED;
  
  	spin_unlock_irqrestore(ap->lock, flags);
  }
  
  /**
   *	ata_scsi_error - SCSI layer error handler callback
   *	@host: SCSI host on which error occurred
   *
   *	Handles SCSI-layer-thrown error events.
   *
   *	LOCKING:
   *	Inherited from SCSI layer (none, can sleep)
   *
   *	RETURNS:
   *	Zero.
   */
  void ata_scsi_error(struct Scsi_Host *host)
  {
  	struct ata_port *ap = ata_shost_to_port(host);
  	unsigned long flags;
  	LIST_HEAD(eh_work_q);
  
  	DPRINTK("ENTER\n");
  
  	spin_lock_irqsave(host->host_lock, flags);
  	list_splice_init(&host->eh_cmd_q, &eh_work_q);
  	spin_unlock_irqrestore(host->host_lock, flags);
  
  	ata_scsi_cmd_error_handler(host, ap, &eh_work_q);
  
  	/* If we timed raced normal completion and there is nothing to
  	   recover nr_timedout == 0 why exactly are we doing error recovery ? */
  	ata_scsi_port_error_handler(host, ap);
  
  	/* finish or retry handled scmd's and clean up */
  	WARN_ON(host->host_failed || !list_empty(&eh_work_q));
  
  	DPRINTK("EXIT\n");
  }
  
  /**
   * ata_scsi_cmd_error_handler - error callback for a list of commands
   * @host:	scsi host containing the port
   * @ap:		ATA port within the host
   * @eh_work_q:	list of commands to process
   *
   * process the given list of commands and return those finished to the
   * ap->eh_done_q.  This function is the first part of the libata error
   * handler which processes a given list of failed commands.
   */
  void ata_scsi_cmd_error_handler(struct Scsi_Host *host, struct ata_port *ap,
  				struct list_head *eh_work_q)
  {
  	int i;
  	unsigned long flags;
  
  	/* make sure sff pio task is not running */
  	ata_sff_flush_pio_task(ap);
  
  	/* synchronize with host lock and sort out timeouts */
  
  	/* For new EH, all qcs are finished in one of three ways -
  	 * normal completion, error completion, and SCSI timeout.
  	 * Both completions can race against SCSI timeout.  When normal
  	 * completion wins, the qc never reaches EH.  When error
  	 * completion wins, the qc has ATA_QCFLAG_FAILED set.
  	 *
  	 * When SCSI timeout wins, things are a bit more complex.
  	 * Normal or error completion can occur after the timeout but
  	 * before this point.  In such cases, both types of
  	 * completions are honored.  A scmd is determined to have
  	 * timed out iff its associated qc is active and not failed.
  	 */
  	if (ap->ops->error_handler) {
  		struct scsi_cmnd *scmd, *tmp;
  		int nr_timedout = 0;
  
  		spin_lock_irqsave(ap->lock, flags);
  
  		/* This must occur under the ap->lock as we don't want
  		   a polled recovery to race the real interrupt handler
  
  		   The lost_interrupt handler checks for any completed but
  		   non-notified command and completes much like an IRQ handler.
  
  		   We then fall into the error recovery code which will treat
  		   this as if normal completion won the race */
  
  		if (ap->ops->lost_interrupt)
  			ap->ops->lost_interrupt(ap);
  
  		list_for_each_entry_safe(scmd, tmp, eh_work_q, eh_entry) {
  			struct ata_queued_cmd *qc;
  
  			for (i = 0; i < ATA_MAX_QUEUE; i++) {
  				qc = __ata_qc_from_tag(ap, i);
  				if (qc->flags & ATA_QCFLAG_ACTIVE &&
  				    qc->scsicmd == scmd)
  					break;
  			}
  
  			if (i < ATA_MAX_QUEUE) {
  				/* the scmd has an associated qc */
  				if (!(qc->flags & ATA_QCFLAG_FAILED)) {
  					/* which hasn't failed yet, timeout */
  					qc->err_mask |= AC_ERR_TIMEOUT;
  					qc->flags |= ATA_QCFLAG_FAILED;
  					nr_timedout++;
  				}
  			} else {
  				/* Normal completion occurred after
  				 * SCSI timeout but before this point.
  				 * Successfully complete it.
  				 */
  				scmd->retries = scmd->allowed;
  				scsi_eh_finish_cmd(scmd, &ap->eh_done_q);
  			}
  		}
  
  		/* If we have timed out qcs.  They belong to EH from
  		 * this point but the state of the controller is
  		 * unknown.  Freeze the port to make sure the IRQ
  		 * handler doesn't diddle with those qcs.  This must
  		 * be done atomically w.r.t. setting QCFLAG_FAILED.
  		 */
  		if (nr_timedout)
  			__ata_port_freeze(ap);
  
  		spin_unlock_irqrestore(ap->lock, flags);
  
  		/* initialize eh_tries */
  		ap->eh_tries = ATA_EH_MAX_TRIES;
  	} else
  		spin_unlock_wait(ap->lock);
  
  }
  EXPORT_SYMBOL(ata_scsi_cmd_error_handler);
  
  /**
   * ata_scsi_port_error_handler - recover the port after the commands
   * @host:	SCSI host containing the port
   * @ap:		the ATA port
   *
   * Handle the recovery of the port @ap after all the commands
   * have been recovered.
   */
  void ata_scsi_port_error_handler(struct Scsi_Host *host, struct ata_port *ap)
  {
  	unsigned long flags;
  
  	/* invoke error handler */
  	if (ap->ops->error_handler) {
  		struct ata_link *link;
  
  		/* acquire EH ownership */
  		ata_eh_acquire(ap);
   repeat:
  		/* kill fast drain timer */
  		del_timer_sync(&ap->fastdrain_timer);
  
  		/* process port resume request */
  		ata_eh_handle_port_resume(ap);
  
  		/* fetch & clear EH info */
  		spin_lock_irqsave(ap->lock, flags);
  
  		ata_for_each_link(link, ap, HOST_FIRST) {
  			struct ata_eh_context *ehc = &link->eh_context;
  			struct ata_device *dev;
  
  			memset(&link->eh_context, 0, sizeof(link->eh_context));
  			link->eh_context.i = link->eh_info;
  			memset(&link->eh_info, 0, sizeof(link->eh_info));
  
  			ata_for_each_dev(dev, link, ENABLED) {
  				int devno = dev->devno;
  
  				ehc->saved_xfer_mode[devno] = dev->xfer_mode;
  				if (ata_ncq_enabled(dev))
  					ehc->saved_ncq_enabled |= 1 << devno;
  			}
  		}
  
  		ap->pflags |= ATA_PFLAG_EH_IN_PROGRESS;
  		ap->pflags &= ~ATA_PFLAG_EH_PENDING;
  		ap->excl_link = NULL;	/* don't maintain exclusion over EH */
  
  		spin_unlock_irqrestore(ap->lock, flags);
  
  		/* invoke EH, skip if unloading or suspended */
  		if (!(ap->pflags & (ATA_PFLAG_UNLOADING | ATA_PFLAG_SUSPENDED)))
  			ap->ops->error_handler(ap);
  		else {
  			/* if unloading, commence suicide */
  			if ((ap->pflags & ATA_PFLAG_UNLOADING) &&
  			    !(ap->pflags & ATA_PFLAG_UNLOADED))
  				ata_eh_unload(ap);
  			ata_eh_finish(ap);
  		}
  
  		/* process port suspend request */
  		ata_eh_handle_port_suspend(ap);
  
  		/* Exception might have happened after ->error_handler
  		 * recovered the port but before this point.  Repeat
  		 * EH in such case.
  		 */
  		spin_lock_irqsave(ap->lock, flags);
  
  		if (ap->pflags & ATA_PFLAG_EH_PENDING) {
  			if (--ap->eh_tries) {
  				spin_unlock_irqrestore(ap->lock, flags);
  				goto repeat;
  			}
  			ata_port_err(ap,
  				     "EH pending after %d tries, giving up\n",
  				     ATA_EH_MAX_TRIES);
  			ap->pflags &= ~ATA_PFLAG_EH_PENDING;
  		}
  
  		/* this run is complete, make sure EH info is clear */
  		ata_for_each_link(link, ap, HOST_FIRST)
  			memset(&link->eh_info, 0, sizeof(link->eh_info));
  
  		/* Clear host_eh_scheduled while holding ap->lock such
  		 * that if exception occurs after this point but
  		 * before EH completion, SCSI midlayer will
  		 * re-initiate EH.
  		 */
  		host->host_eh_scheduled = 0;
  
  		spin_unlock_irqrestore(ap->lock, flags);
  		ata_eh_release(ap);
  	} else {
  		WARN_ON(ata_qc_from_tag(ap, ap->link.active_tag) == NULL);
  		ap->ops->eng_timeout(ap);
  	}
  
  	scsi_eh_flush_done_q(&ap->eh_done_q);
  
  	/* clean up */
  	spin_lock_irqsave(ap->lock, flags);
  
  	if (ap->pflags & ATA_PFLAG_LOADING)
  		ap->pflags &= ~ATA_PFLAG_LOADING;
  	else if (ap->pflags & ATA_PFLAG_SCSI_HOTPLUG)
  		schedule_delayed_work(&ap->hotplug_task, 0);
  
  	if (ap->pflags & ATA_PFLAG_RECOVERED)
  		ata_port_info(ap, "EH complete\n");
  
  	ap->pflags &= ~(ATA_PFLAG_SCSI_HOTPLUG | ATA_PFLAG_RECOVERED);
  
  	/* tell wait_eh that we're done */
  	ap->pflags &= ~ATA_PFLAG_EH_IN_PROGRESS;
  	wake_up_all(&ap->eh_wait_q);
  
  	spin_unlock_irqrestore(ap->lock, flags);
  }
  EXPORT_SYMBOL_GPL(ata_scsi_port_error_handler);
  
  /**
   *	ata_port_wait_eh - Wait for the currently pending EH to complete
   *	@ap: Port to wait EH for
   *
   *	Wait until the currently pending EH is complete.
   *
   *	LOCKING:
   *	Kernel thread context (may sleep).
   */
  void ata_port_wait_eh(struct ata_port *ap)
  {
  	unsigned long flags;
  	DEFINE_WAIT(wait);
  
   retry:
  	spin_lock_irqsave(ap->lock, flags);
  
  	while (ap->pflags & (ATA_PFLAG_EH_PENDING | ATA_PFLAG_EH_IN_PROGRESS)) {
  		prepare_to_wait(&ap->eh_wait_q, &wait, TASK_UNINTERRUPTIBLE);
  		spin_unlock_irqrestore(ap->lock, flags);
  		schedule();
  		spin_lock_irqsave(ap->lock, flags);
  	}
  	finish_wait(&ap->eh_wait_q, &wait);
  
  	spin_unlock_irqrestore(ap->lock, flags);
  
  	/* make sure SCSI EH is complete */
  	if (scsi_host_in_recovery(ap->scsi_host)) {
  		ata_msleep(ap, 10);
  		goto retry;
  	}
  }
  EXPORT_SYMBOL_GPL(ata_port_wait_eh);
  
  static int ata_eh_nr_in_flight(struct ata_port *ap)
  {
  	unsigned int tag;
  	int nr = 0;
  
  	/* count only non-internal commands */
  	for (tag = 0; tag < ATA_MAX_QUEUE - 1; tag++)
  		if (ata_qc_from_tag(ap, tag))
  			nr++;
  
  	return nr;
  }
  
  void ata_eh_fastdrain_timerfn(unsigned long arg)
  {
  	struct ata_port *ap = (void *)arg;
  	unsigned long flags;
  	int cnt;
  
  	spin_lock_irqsave(ap->lock, flags);
  
  	cnt = ata_eh_nr_in_flight(ap);
  
  	/* are we done? */
  	if (!cnt)
  		goto out_unlock;
  
  	if (cnt == ap->fastdrain_cnt) {
  		unsigned int tag;
  
  		/* No progress during the last interval, tag all
  		 * in-flight qcs as timed out and freeze the port.
  		 */
  		for (tag = 0; tag < ATA_MAX_QUEUE - 1; tag++) {
  			struct ata_queued_cmd *qc = ata_qc_from_tag(ap, tag);
  			if (qc)
  				qc->err_mask |= AC_ERR_TIMEOUT;
  		}
  
  		ata_port_freeze(ap);
  	} else {
  		/* some qcs have finished, give it another chance */
  		ap->fastdrain_cnt = cnt;
  		ap->fastdrain_timer.expires =
  			ata_deadline(jiffies, ATA_EH_FASTDRAIN_INTERVAL);
  		add_timer(&ap->fastdrain_timer);
  	}
  
   out_unlock:
  	spin_unlock_irqrestore(ap->lock, flags);
  }
  
  /**
   *	ata_eh_set_pending - set ATA_PFLAG_EH_PENDING and activate fast drain
   *	@ap: target ATA port
   *	@fastdrain: activate fast drain
   *
   *	Set ATA_PFLAG_EH_PENDING and activate fast drain if @fastdrain
   *	is non-zero and EH wasn't pending before.  Fast drain ensures
   *	that EH kicks in in timely manner.
   *
   *	LOCKING:
   *	spin_lock_irqsave(host lock)
   */
  static void ata_eh_set_pending(struct ata_port *ap, int fastdrain)
  {
  	int cnt;
  
  	/* already scheduled? */
  	if (ap->pflags & ATA_PFLAG_EH_PENDING)
  		return;
  
  	ap->pflags |= ATA_PFLAG_EH_PENDING;
  
  	if (!fastdrain)
  		return;
  
  	/* do we have in-flight qcs? */
  	cnt = ata_eh_nr_in_flight(ap);
  	if (!cnt)
  		return;
  
  	/* activate fast drain */
  	ap->fastdrain_cnt = cnt;
  	ap->fastdrain_timer.expires =
  		ata_deadline(jiffies, ATA_EH_FASTDRAIN_INTERVAL);
  	add_timer(&ap->fastdrain_timer);
  }
  
  /**
   *	ata_qc_schedule_eh - schedule qc for error handling
   *	@qc: command to schedule error handling for
   *
   *	Schedule error handling for @qc.  EH will kick in as soon as
   *	other commands are drained.
   *
   *	LOCKING:
   *	spin_lock_irqsave(host lock)
   */
  void ata_qc_schedule_eh(struct ata_queued_cmd *qc)
  {
  	struct ata_port *ap = qc->ap;
  	struct request_queue *q = qc->scsicmd->device->request_queue;
  	unsigned long flags;
  
  	WARN_ON(!ap->ops->error_handler);
  
  	qc->flags |= ATA_QCFLAG_FAILED;
  	ata_eh_set_pending(ap, 1);
  
  	/* The following will fail if timeout has already expired.
  	 * ata_scsi_error() takes care of such scmds on EH entry.
  	 * Note that ATA_QCFLAG_FAILED is unconditionally set after
  	 * this function completes.
  	 */
  	spin_lock_irqsave(q->queue_lock, flags);
  	blk_abort_request(qc->scsicmd->request);
  	spin_unlock_irqrestore(q->queue_lock, flags);
  }
  
  /**
   *	ata_port_schedule_eh - schedule error handling without a qc
   *	@ap: ATA port to schedule EH for
   *
   *	Schedule error handling for @ap.  EH will kick in as soon as
   *	all commands are drained.
   *
   *	LOCKING:
   *	spin_lock_irqsave(host lock)
   */
  void ata_port_schedule_eh(struct ata_port *ap)
  {
  	WARN_ON(!ap->ops->error_handler);
  
  	if (ap->pflags & ATA_PFLAG_INITIALIZING)
  		return;
  
  	ata_eh_set_pending(ap, 1);
  	scsi_schedule_eh(ap->scsi_host);
  
  	DPRINTK("port EH scheduled\n");
  }
  
  static int ata_do_link_abort(struct ata_port *ap, struct ata_link *link)
  {
  	int tag, nr_aborted = 0;
  
  	WARN_ON(!ap->ops->error_handler);
  
  	/* we're gonna abort all commands, no need for fast drain */
  	ata_eh_set_pending(ap, 0);
  
  	for (tag = 0; tag < ATA_MAX_QUEUE; tag++) {
  		struct ata_queued_cmd *qc = ata_qc_from_tag(ap, tag);
  
  		if (qc && (!link || qc->dev->link == link)) {
  			qc->flags |= ATA_QCFLAG_FAILED;
  			ata_qc_complete(qc);
  			nr_aborted++;
  		}
  	}
  
  	if (!nr_aborted)
  		ata_port_schedule_eh(ap);
  
  	return nr_aborted;
  }
  
  /**
   *	ata_link_abort - abort all qc's on the link
   *	@link: ATA link to abort qc's for
   *
   *	Abort all active qc's active on @link and schedule EH.
   *
   *	LOCKING:
   *	spin_lock_irqsave(host lock)
   *
   *	RETURNS:
   *	Number of aborted qc's.
   */
  int ata_link_abort(struct ata_link *link)
  {
  	return ata_do_link_abort(link->ap, link);
  }
  
  /**
   *	ata_port_abort - abort all qc's on the port
   *	@ap: ATA port to abort qc's for
   *
   *	Abort all active qc's of @ap and schedule EH.
   *
   *	LOCKING:
   *	spin_lock_irqsave(host_set lock)
   *
   *	RETURNS:
   *	Number of aborted qc's.
   */
  int ata_port_abort(struct ata_port *ap)
  {
  	return ata_do_link_abort(ap, NULL);
  }
  
  /**
   *	__ata_port_freeze - freeze port
   *	@ap: ATA port to freeze
   *
   *	This function is called when HSM violation or some other
   *	condition disrupts normal operation of the port.  Frozen port
   *	is not allowed to perform any operation until the port is
   *	thawed, which usually follows a successful reset.
   *
   *	ap->ops->freeze() callback can be used for freezing the port
   *	hardware-wise (e.g. mask interrupt and stop DMA engine).  If a
   *	port cannot be frozen hardware-wise, the interrupt handler
   *	must ack and clear interrupts unconditionally while the port
   *	is frozen.
   *
   *	LOCKING:
   *	spin_lock_irqsave(host lock)
   */
  static void __ata_port_freeze(struct ata_port *ap)
  {
  	WARN_ON(!ap->ops->error_handler);
  
  	if (ap->ops->freeze)
  		ap->ops->freeze(ap);
  
  	ap->pflags |= ATA_PFLAG_FROZEN;
  
  	DPRINTK("ata%u port frozen\n", ap->print_id);
  }
  
  /**
   *	ata_port_freeze - abort & freeze port
   *	@ap: ATA port to freeze
   *
   *	Abort and freeze @ap.  The freeze operation must be called
   *	first, because some hardware requires special operations
   *	before the taskfile registers are accessible.
   *
   *	LOCKING:
   *	spin_lock_irqsave(host lock)
   *
   *	RETURNS:
   *	Number of aborted commands.
   */
  int ata_port_freeze(struct ata_port *ap)
  {
  	int nr_aborted;
  
  	WARN_ON(!ap->ops->error_handler);
  
  	__ata_port_freeze(ap);
  	nr_aborted = ata_port_abort(ap);
  
  	return nr_aborted;
  }
  
  /**
   *	sata_async_notification - SATA async notification handler
   *	@ap: ATA port where async notification is received
   *
   *	Handler to be called when async notification via SDB FIS is
   *	received.  This function schedules EH if necessary.
   *
   *	LOCKING:
   *	spin_lock_irqsave(host lock)
   *
   *	RETURNS:
   *	1 if EH is scheduled, 0 otherwise.
   */
  int sata_async_notification(struct ata_port *ap)
  {
  	u32 sntf;
  	int rc;
  
  	if (!(ap->flags & ATA_FLAG_AN))
  		return 0;
  
  	rc = sata_scr_read(&ap->link, SCR_NOTIFICATION, &sntf);
  	if (rc == 0)
  		sata_scr_write(&ap->link, SCR_NOTIFICATION, sntf);
  
  	if (!sata_pmp_attached(ap) || rc) {
  		/* PMP is not attached or SNTF is not available */
  		if (!sata_pmp_attached(ap)) {
  			/* PMP is not attached.  Check whether ATAPI
  			 * AN is configured.  If so, notify media
  			 * change.
  			 */
  			struct ata_device *dev = ap->link.device;
  
  			if ((dev->class == ATA_DEV_ATAPI) &&
  			    (dev->flags & ATA_DFLAG_AN))
  				ata_scsi_media_change_notify(dev);
  			return 0;
  		} else {
  			/* PMP is attached but SNTF is not available.
  			 * ATAPI async media change notification is
  			 * not used.  The PMP must be reporting PHY
  			 * status change, schedule EH.
  			 */
  			ata_port_schedule_eh(ap);
  			return 1;
  		}
  	} else {
  		/* PMP is attached and SNTF is available */
  		struct ata_link *link;
  
  		/* check and notify ATAPI AN */
  		ata_for_each_link(link, ap, EDGE) {
  			if (!(sntf & (1 << link->pmp)))
  				continue;
  
  			if ((link->device->class == ATA_DEV_ATAPI) &&
  			    (link->device->flags & ATA_DFLAG_AN))
  				ata_scsi_media_change_notify(link->device);
  		}
  
  		/* If PMP is reporting that PHY status of some
  		 * downstream ports has changed, schedule EH.
  		 */
  		if (sntf & (1 << SATA_PMP_CTRL_PORT)) {
  			ata_port_schedule_eh(ap);
  			return 1;
  		}
  
  		return 0;
  	}
  }
  
  /**
   *	ata_eh_freeze_port - EH helper to freeze port
   *	@ap: ATA port to freeze
   *
   *	Freeze @ap.
   *
   *	LOCKING:
   *	None.
   */
  void ata_eh_freeze_port(struct ata_port *ap)
  {
  	unsigned long flags;
  
  	if (!ap->ops->error_handler)
  		return;
  
  	spin_lock_irqsave(ap->lock, flags);
  	__ata_port_freeze(ap);
  	spin_unlock_irqrestore(ap->lock, flags);
  }
  
  /**
   *	ata_port_thaw_port - EH helper to thaw port
   *	@ap: ATA port to thaw
   *
   *	Thaw frozen port @ap.
   *
   *	LOCKING:
   *	None.
   */
  void ata_eh_thaw_port(struct ata_port *ap)
  {
  	unsigned long flags;
  
  	if (!ap->ops->error_handler)
  		return;
  
  	spin_lock_irqsave(ap->lock, flags);
  
  	ap->pflags &= ~ATA_PFLAG_FROZEN;
  
  	if (ap->ops->thaw)
  		ap->ops->thaw(ap);
  
  	spin_unlock_irqrestore(ap->lock, flags);
  
  	DPRINTK("ata%u port thawed\n", ap->print_id);
  }
  
  static void ata_eh_scsidone(struct scsi_cmnd *scmd)
  {
  	/* nada */
  }
  
  static void __ata_eh_qc_complete(struct ata_queued_cmd *qc)
  {
  	struct ata_port *ap = qc->ap;
  	struct scsi_cmnd *scmd = qc->scsicmd;
  	unsigned long flags;
  
  	spin_lock_irqsave(ap->lock, flags);
  	qc->scsidone = ata_eh_scsidone;
  	__ata_qc_complete(qc);
  	WARN_ON(ata_tag_valid(qc->tag));
  	spin_unlock_irqrestore(ap->lock, flags);
  
  	scsi_eh_finish_cmd(scmd, &ap->eh_done_q);
  }
  
  /**
   *	ata_eh_qc_complete - Complete an active ATA command from EH
   *	@qc: Command to complete
   *
   *	Indicate to the mid and upper layers that an ATA command has
   *	completed.  To be used from EH.
   */
  void ata_eh_qc_complete(struct ata_queued_cmd *qc)
  {
  	struct scsi_cmnd *scmd = qc->scsicmd;
  	scmd->retries = scmd->allowed;
  	__ata_eh_qc_complete(qc);
  }
  
  /**
   *	ata_eh_qc_retry - Tell midlayer to retry an ATA command after EH
   *	@qc: Command to retry
   *
   *	Indicate to the mid and upper layers that an ATA command
   *	should be retried.  To be used from EH.
   *
   *	SCSI midlayer limits the number of retries to scmd->allowed.
   *	scmd->retries is decremented for commands which get retried
   *	due to unrelated failures (qc->err_mask is zero).
   */
  void ata_eh_qc_retry(struct ata_queued_cmd *qc)
  {
  	struct scsi_cmnd *scmd = qc->scsicmd;
  	if (!qc->err_mask && scmd->retries)
  		scmd->retries--;
  	__ata_eh_qc_complete(qc);
  }
  
  /**
   *	ata_dev_disable - disable ATA device
   *	@dev: ATA device to disable
   *
   *	Disable @dev.
   *
   *	Locking:
   *	EH context.
   */
  void ata_dev_disable(struct ata_device *dev)
  {
  	if (!ata_dev_enabled(dev))
  		return;
  
  	if (ata_msg_drv(dev->link->ap))
  		ata_dev_warn(dev, "disabled\n");
  	ata_acpi_on_disable(dev);
  	ata_down_xfermask_limit(dev, ATA_DNXFER_FORCE_PIO0 | ATA_DNXFER_QUIET);
  	dev->class++;
  
  	/* From now till the next successful probe, ering is used to
  	 * track probe failures.  Clear accumulated device error info.
  	 */
  	ata_ering_clear(&dev->ering);
  }
  
  /**
   *	ata_eh_detach_dev - detach ATA device
   *	@dev: ATA device to detach
   *
   *	Detach @dev.
   *
   *	LOCKING:
   *	None.
   */
  void ata_eh_detach_dev(struct ata_device *dev)
  {
  	struct ata_link *link = dev->link;
  	struct ata_port *ap = link->ap;
  	struct ata_eh_context *ehc = &link->eh_context;
  	unsigned long flags;
  
  	ata_dev_disable(dev);
  
  	spin_lock_irqsave(ap->lock, flags);
  
  	dev->flags &= ~ATA_DFLAG_DETACH;
  
  	if (ata_scsi_offline_dev(dev)) {
  		dev->flags |= ATA_DFLAG_DETACHED;
  		ap->pflags |= ATA_PFLAG_SCSI_HOTPLUG;
  	}
  
  	/* clear per-dev EH info */
  	ata_eh_clear_action(link, dev, &link->eh_info, ATA_EH_PERDEV_MASK);
  	ata_eh_clear_action(link, dev, &link->eh_context.i, ATA_EH_PERDEV_MASK);
  	ehc->saved_xfer_mode[dev->devno] = 0;
  	ehc->saved_ncq_enabled &= ~(1 << dev->devno);
  
  	spin_unlock_irqrestore(ap->lock, flags);
  }
  
  /**
   *	ata_eh_about_to_do - about to perform eh_action
   *	@link: target ATA link
   *	@dev: target ATA dev for per-dev action (can be NULL)
   *	@action: action about to be performed
   *
   *	Called just before performing EH actions to clear related bits
   *	in @link->eh_info such that eh actions are not unnecessarily
   *	repeated.
   *
   *	LOCKING:
   *	None.
   */
  void ata_eh_about_to_do(struct ata_link *link, struct ata_device *dev,
  			unsigned int action)
  {
  	struct ata_port *ap = link->ap;
  	struct ata_eh_info *ehi = &link->eh_info;
  	struct ata_eh_context *ehc = &link->eh_context;
  	unsigned long flags;
  
  	spin_lock_irqsave(ap->lock, flags);
  
  	ata_eh_clear_action(link, dev, ehi, action);
  
  	/* About to take EH action, set RECOVERED.  Ignore actions on
  	 * slave links as master will do them again.
  	 */
  	if (!(ehc->i.flags & ATA_EHI_QUIET) && link != ap->slave_link)
  		ap->pflags |= ATA_PFLAG_RECOVERED;
  
  	spin_unlock_irqrestore(ap->lock, flags);
  }
  
  /**
   *	ata_eh_done - EH action complete
  *	@ap: target ATA port
   *	@dev: target ATA dev for per-dev action (can be NULL)
   *	@action: action just completed
   *
   *	Called right after performing EH actions to clear related bits
   *	in @link->eh_context.
   *
   *	LOCKING:
   *	None.
   */
  void ata_eh_done(struct ata_link *link, struct ata_device *dev,
  		 unsigned int action)
  {
  	struct ata_eh_context *ehc = &link->eh_context;
  
  	ata_eh_clear_action(link, dev, &ehc->i, action);
  }
  
  /**
   *	ata_err_string - convert err_mask to descriptive string
   *	@err_mask: error mask to convert to string
   *
   *	Convert @err_mask to descriptive string.  Errors are
   *	prioritized according to severity and only the most severe
   *	error is reported.
   *
   *	LOCKING:
   *	None.
   *
   *	RETURNS:
   *	Descriptive string for @err_mask
   */
  static const char *ata_err_string(unsigned int err_mask)
  {
  	if (err_mask & AC_ERR_HOST_BUS)
  		return "host bus error";
  	if (err_mask & AC_ERR_ATA_BUS)
  		return "ATA bus error";
  	if (err_mask & AC_ERR_TIMEOUT)
  		return "timeout";
  	if (err_mask & AC_ERR_HSM)
  		return "HSM violation";
  	if (err_mask & AC_ERR_SYSTEM)
  		return "internal error";
  	if (err_mask & AC_ERR_MEDIA)
  		return "media error";
  	if (err_mask & AC_ERR_INVALID)
  		return "invalid argument";
  	if (err_mask & AC_ERR_DEV)
  		return "device error";
  	return "unknown error";
  }
  
  /**
   *	ata_read_log_page - read a specific log page
   *	@dev: target device
   *	@page: page to read
   *	@buf: buffer to store read page
   *	@sectors: number of sectors to read
   *
   *	Read log page using READ_LOG_EXT command.
   *
   *	LOCKING:
   *	Kernel thread context (may sleep).
   *
   *	RETURNS:
   *	0 on success, AC_ERR_* mask otherwise.
   */
  static unsigned int ata_read_log_page(struct ata_device *dev,
  				      u8 page, void *buf, unsigned int sectors)
  {
  	struct ata_taskfile tf;
  	unsigned int err_mask;
  
  	DPRINTK("read log page - page %d\n", page);
  
  	ata_tf_init(dev, &tf);
  	tf.command = ATA_CMD_READ_LOG_EXT;
  	tf.lbal = page;
  	tf.nsect = sectors;
  	tf.hob_nsect = sectors >> 8;
  	tf.flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_LBA48 | ATA_TFLAG_DEVICE;
  	tf.protocol = ATA_PROT_PIO;
  
  	err_mask = ata_exec_internal(dev, &tf, NULL, DMA_FROM_DEVICE,
  				     buf, sectors * ATA_SECT_SIZE, 0);
  
  	DPRINTK("EXIT, err_mask=%x\n", err_mask);
  	return err_mask;
  }
  
  /**
   *	ata_eh_read_log_10h - Read log page 10h for NCQ error details
   *	@dev: Device to read log page 10h from
   *	@tag: Resulting tag of the failed command
   *	@tf: Resulting taskfile registers of the failed command
   *
   *	Read log page 10h to obtain NCQ error details and clear error
   *	condition.
   *
   *	LOCKING:
   *	Kernel thread context (may sleep).
   *
   *	RETURNS:
   *	0 on success, -errno otherwise.
   */
  static int ata_eh_read_log_10h(struct ata_device *dev,
  			       int *tag, struct ata_taskfile *tf)
  {
  	u8 *buf = dev->link->ap->sector_buf;
  	unsigned int err_mask;
  	u8 csum;
  	int i;
  
  	err_mask = ata_read_log_page(dev, ATA_LOG_SATA_NCQ, buf, 1);
  	if (err_mask)
  		return -EIO;
  
  	csum = 0;
  	for (i = 0; i < ATA_SECT_SIZE; i++)
  		csum += buf[i];
  	if (csum)
  		ata_dev_warn(dev, "invalid checksum 0x%x on log page 10h\n",
  			     csum);
  
  	if (buf[0] & 0x80)
  		return -ENOENT;
  
  	*tag = buf[0] & 0x1f;
  
  	tf->command = buf[2];
  	tf->feature = buf[3];
  	tf->lbal = buf[4];
  	tf->lbam = buf[5];
  	tf->lbah = buf[6];
  	tf->device = buf[7];
  	tf->hob_lbal = buf[8];
  	tf->hob_lbam = buf[9];
  	tf->hob_lbah = buf[10];
  	tf->nsect = buf[12];
  	tf->hob_nsect = buf[13];
  
  	return 0;
  }
  
  /**
   *	atapi_eh_tur - perform ATAPI TEST_UNIT_READY
   *	@dev: target ATAPI device
   *	@r_sense_key: out parameter for sense_key
   *
   *	Perform ATAPI TEST_UNIT_READY.
   *
   *	LOCKING:
   *	EH context (may sleep).
   *
   *	RETURNS:
   *	0 on success, AC_ERR_* mask on failure.
   */
  static unsigned int atapi_eh_tur(struct ata_device *dev, u8 *r_sense_key)
  {
  	u8 cdb[ATAPI_CDB_LEN] = { TEST_UNIT_READY, 0, 0, 0, 0, 0 };
  	struct ata_taskfile tf;
  	unsigned int err_mask;
  
  	ata_tf_init(dev, &tf);
  
  	tf.flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE;
  	tf.command = ATA_CMD_PACKET;
  	tf.protocol = ATAPI_PROT_NODATA;
  
  	err_mask = ata_exec_internal(dev, &tf, cdb, DMA_NONE, NULL, 0, 0);
  	if (err_mask == AC_ERR_DEV)
  		*r_sense_key = tf.feature >> 4;
  	return err_mask;
  }
  
  /**
   *	atapi_eh_request_sense - perform ATAPI REQUEST_SENSE
   *	@dev: device to perform REQUEST_SENSE to
   *	@sense_buf: result sense data buffer (SCSI_SENSE_BUFFERSIZE bytes long)
   *	@dfl_sense_key: default sense key to use
   *
   *	Perform ATAPI REQUEST_SENSE after the device reported CHECK
   *	SENSE.  This function is EH helper.
   *
   *	LOCKING:
   *	Kernel thread context (may sleep).
   *
   *	RETURNS:
   *	0 on success, AC_ERR_* mask on failure
   */
  static unsigned int atapi_eh_request_sense(struct ata_device *dev,
  					   u8 *sense_buf, u8 dfl_sense_key)
  {
  	u8 cdb[ATAPI_CDB_LEN] =
  		{ REQUEST_SENSE, 0, 0, 0, SCSI_SENSE_BUFFERSIZE, 0 };
  	struct ata_port *ap = dev->link->ap;
  	struct ata_taskfile tf;
  
  	DPRINTK("ATAPI request sense\n");
  
  	/* FIXME: is this needed? */
  	memset(sense_buf, 0, SCSI_SENSE_BUFFERSIZE);
  
  	/* initialize sense_buf with the error register,
  	 * for the case where they are -not- overwritten
  	 */
  	sense_buf[0] = 0x70;
  	sense_buf[2] = dfl_sense_key;
  
  	/* some devices time out if garbage left in tf */
  	ata_tf_init(dev, &tf);
  
  	tf.flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE;
  	tf.command = ATA_CMD_PACKET;
  
  	/* is it pointless to prefer PIO for "safety reasons"? */
  	if (ap->flags & ATA_FLAG_PIO_DMA) {
  		tf.protocol = ATAPI_PROT_DMA;
  		tf.feature |= ATAPI_PKT_DMA;
  	} else {
  		tf.protocol = ATAPI_PROT_PIO;
  		tf.lbam = SCSI_SENSE_BUFFERSIZE;
  		tf.lbah = 0;
  	}
  
  	return ata_exec_internal(dev, &tf, cdb, DMA_FROM_DEVICE,
  				 sense_buf, SCSI_SENSE_BUFFERSIZE, 0);
  }
  
  /**
   *	ata_eh_analyze_serror - analyze SError for a failed port
   *	@link: ATA link to analyze SError for
   *
   *	Analyze SError if available and further determine cause of
   *	failure.
   *
   *	LOCKING:
   *	None.
   */
  static void ata_eh_analyze_serror(struct ata_link *link)
  {
  	struct ata_eh_context *ehc = &link->eh_context;
  	u32 serror = ehc->i.serror;
  	unsigned int err_mask = 0, action = 0;
  	u32 hotplug_mask;
  
  	if (serror & (SERR_PERSISTENT | SERR_DATA)) {
  		err_mask |= AC_ERR_ATA_BUS;
  		action |= ATA_EH_RESET;
  	}
  	if (serror & SERR_PROTOCOL) {
  		err_mask |= AC_ERR_HSM;
  		action |= ATA_EH_RESET;
  	}
  	if (serror & SERR_INTERNAL) {
  		err_mask |= AC_ERR_SYSTEM;
  		action |= ATA_EH_RESET;
  	}
  
  	/* Determine whether a hotplug event has occurred.  Both
  	 * SError.N/X are considered hotplug events for enabled or
  	 * host links.  For disabled PMP links, only N bit is
  	 * considered as X bit is left at 1 for link plugging.
  	 */
  	if (link->lpm_policy > ATA_LPM_MAX_POWER)
  		hotplug_mask = 0;	/* hotplug doesn't work w/ LPM */
  	else if (!(link->flags & ATA_LFLAG_DISABLED) || ata_is_host_link(link))
  		hotplug_mask = SERR_PHYRDY_CHG | SERR_DEV_XCHG;
  	else
  		hotplug_mask = SERR_PHYRDY_CHG;
  
  	if (serror & hotplug_mask)
  		ata_ehi_hotplugged(&ehc->i);
  
  	ehc->i.err_mask |= err_mask;
  	ehc->i.action |= action;
  }
  
  /**
   *	ata_eh_analyze_ncq_error - analyze NCQ error
   *	@link: ATA link to analyze NCQ error for
   *
   *	Read log page 10h, determine the offending qc and acquire
   *	error status TF.  For NCQ device errors, all LLDDs have to do
   *	is setting AC_ERR_DEV in ehi->err_mask.  This function takes
   *	care of the rest.
   *
   *	LOCKING:
   *	Kernel thread context (may sleep).
   */
  void ata_eh_analyze_ncq_error(struct ata_link *link)
  {
  	struct ata_port *ap = link->ap;
  	struct ata_eh_context *ehc = &link->eh_context;
  	struct ata_device *dev = link->device;
  	struct ata_queued_cmd *qc;
  	struct ata_taskfile tf;
  	int tag, rc;
  
  	/* if frozen, we can't do much */
  	if (ap->pflags & ATA_PFLAG_FROZEN)
  		return;
  
  	/* is it NCQ device error? */
  	if (!link->sactive || !(ehc->i.err_mask & AC_ERR_DEV))
  		return;
  
  	/* has LLDD analyzed already? */
  	for (tag = 0; tag < ATA_MAX_QUEUE; tag++) {
  		qc = __ata_qc_from_tag(ap, tag);
  
  		if (!(qc->flags & ATA_QCFLAG_FAILED))
  			continue;
  
  		if (qc->err_mask)
  			return;
  	}
  
  	/* okay, this error is ours */
  	memset(&tf, 0, sizeof(tf));
  	rc = ata_eh_read_log_10h(dev, &tag, &tf);
  	if (rc) {
  		ata_link_err(link, "failed to read log page 10h (errno=%d)\n",
  			     rc);
  		return;
  	}
  
  	if (!(link->sactive & (1 << tag))) {
  		ata_link_err(link, "log page 10h reported inactive tag %d\n",
  			     tag);
  		return;
  	}
  
  	/* we've got the perpetrator, condemn it */
  	qc = __ata_qc_from_tag(ap, tag);
  	memcpy(&qc->result_tf, &tf, sizeof(tf));
  	qc->result_tf.flags = ATA_TFLAG_ISADDR | ATA_TFLAG_LBA | ATA_TFLAG_LBA48;
  	qc->err_mask |= AC_ERR_DEV | AC_ERR_NCQ;
  	ehc->i.err_mask &= ~AC_ERR_DEV;
  }
  
  /**
   *	ata_eh_analyze_tf - analyze taskfile of a failed qc
   *	@qc: qc to analyze
   *	@tf: Taskfile registers to analyze
   *
   *	Analyze taskfile of @qc and further determine cause of
   *	failure.  This function also requests ATAPI sense data if
   *	available.
   *
   *	LOCKING:
   *	Kernel thread context (may sleep).
   *
   *	RETURNS:
   *	Determined recovery action
   */
  static unsigned int ata_eh_analyze_tf(struct ata_queued_cmd *qc,
  				      const struct ata_taskfile *tf)
  {
  	unsigned int tmp, action = 0;
  	u8 stat = tf->command, err = tf->feature;
  
  	if ((stat & (ATA_BUSY | ATA_DRQ | ATA_DRDY)) != ATA_DRDY) {
  		qc->err_mask |= AC_ERR_HSM;
  		return ATA_EH_RESET;
  	}
  
  	if (stat & (ATA_ERR | ATA_DF))
  		qc->err_mask |= AC_ERR_DEV;
  	else
  		return 0;
  
  	switch (qc->dev->class) {
  	case ATA_DEV_ATA:
  		if (err & ATA_ICRC)
  			qc->err_mask |= AC_ERR_ATA_BUS;
  		if (err & ATA_UNC)
  			qc->err_mask |= AC_ERR_MEDIA;
  		if (err & ATA_IDNF)
  			qc->err_mask |= AC_ERR_INVALID;
  		break;
  
  	case ATA_DEV_ATAPI:
  		if (!(qc->ap->pflags & ATA_PFLAG_FROZEN)) {
  			tmp = atapi_eh_request_sense(qc->dev,
  						qc->scsicmd->sense_buffer,
  						qc->result_tf.feature >> 4);
  			if (!tmp) {
  				/* ATA_QCFLAG_SENSE_VALID is used to
  				 * tell atapi_qc_complete() that sense
  				 * data is already valid.
  				 *
  				 * TODO: interpret sense data and set
  				 * appropriate err_mask.
  				 */
  				qc->flags |= ATA_QCFLAG_SENSE_VALID;
  			} else
  				qc->err_mask |= tmp;
  		}
  	}
  
  	if (qc->err_mask & (AC_ERR_HSM | AC_ERR_TIMEOUT | AC_ERR_ATA_BUS))
  		action |= ATA_EH_RESET;
  
  	return action;
  }
  
  static int ata_eh_categorize_error(unsigned int eflags, unsigned int err_mask,
  				   int *xfer_ok)
  {
  	int base = 0;
  
  	if (!(eflags & ATA_EFLAG_DUBIOUS_XFER))
  		*xfer_ok = 1;
  
  	if (!*xfer_ok)
  		base = ATA_ECAT_DUBIOUS_NONE;
  
  	if (err_mask & AC_ERR_ATA_BUS)
  		return base + ATA_ECAT_ATA_BUS;
  
  	if (err_mask & AC_ERR_TIMEOUT)
  		return base + ATA_ECAT_TOUT_HSM;
  
  	if (eflags & ATA_EFLAG_IS_IO) {
  		if (err_mask & AC_ERR_HSM)
  			return base + ATA_ECAT_TOUT_HSM;
  		if ((err_mask &
  		     (AC_ERR_DEV|AC_ERR_MEDIA|AC_ERR_INVALID)) == AC_ERR_DEV)
  			return base + ATA_ECAT_UNK_DEV;
  	}
  
  	return 0;
  }
  
  struct speed_down_verdict_arg {
  	u64 since;
  	int xfer_ok;
  	int nr_errors[ATA_ECAT_NR];
  };
  
  static int speed_down_verdict_cb(struct ata_ering_entry *ent, void *void_arg)
  {
  	struct speed_down_verdict_arg *arg = void_arg;
  	int cat;
  
  	if ((ent->eflags & ATA_EFLAG_OLD_ER) || (ent->timestamp < arg->since))
  		return -1;
  
  	cat = ata_eh_categorize_error(ent->eflags, ent->err_mask,
  				      &arg->xfer_ok);
  	arg->nr_errors[cat]++;
  
  	return 0;
  }
  
  /**
   *	ata_eh_speed_down_verdict - Determine speed down verdict
   *	@dev: Device of interest
   *
   *	This function examines error ring of @dev and determines
   *	whether NCQ needs to be turned off, transfer speed should be
   *	stepped down, or falling back to PIO is necessary.
   *
   *	ECAT_ATA_BUS	: ATA_BUS error for any command
   *
   *	ECAT_TOUT_HSM	: TIMEOUT for any command or HSM violation for
   *			  IO commands
   *
   *	ECAT_UNK_DEV	: Unknown DEV error for IO commands
   *
   *	ECAT_DUBIOUS_*	: Identical to above three but occurred while
   *			  data transfer hasn't been verified.
   *
   *	Verdicts are
   *
   *	NCQ_OFF		: Turn off NCQ.
   *
   *	SPEED_DOWN	: Speed down transfer speed but don't fall back
   *			  to PIO.
   *
   *	FALLBACK_TO_PIO	: Fall back to PIO.
   *
   *	Even if multiple verdicts are returned, only one action is
   *	taken per error.  An action triggered by non-DUBIOUS errors
   *	clears ering, while one triggered by DUBIOUS_* errors doesn't.
   *	This is to expedite speed down decisions right after device is
   *	initially configured.
   *
   *	The followings are speed down rules.  #1 and #2 deal with
   *	DUBIOUS errors.
   *
   *	1. If more than one DUBIOUS_ATA_BUS or DUBIOUS_TOUT_HSM errors
   *	   occurred during last 5 mins, SPEED_DOWN and FALLBACK_TO_PIO.
   *
   *	2. If more than one DUBIOUS_TOUT_HSM or DUBIOUS_UNK_DEV errors
   *	   occurred during last 5 mins, NCQ_OFF.
   *
   *	3. If more than 8 ATA_BUS, TOUT_HSM or UNK_DEV errors
   *	   occurred during last 5 mins, FALLBACK_TO_PIO
   *
   *	4. If more than 3 TOUT_HSM or UNK_DEV errors occurred
   *	   during last 10 mins, NCQ_OFF.
   *
   *	5. If more than 3 ATA_BUS or TOUT_HSM errors, or more than 6
   *	   UNK_DEV errors occurred during last 10 mins, SPEED_DOWN.
   *
   *	LOCKING:
   *	Inherited from caller.
   *
   *	RETURNS:
   *	OR of ATA_EH_SPDN_* flags.
   */
  static unsigned int ata_eh_speed_down_verdict(struct ata_device *dev)
  {
  	const u64 j5mins = 5LLU * 60 * HZ, j10mins = 10LLU * 60 * HZ;
  	u64 j64 = get_jiffies_64();
  	struct speed_down_verdict_arg arg;
  	unsigned int verdict = 0;
  
  	/* scan past 5 mins of error history */
  	memset(&arg, 0, sizeof(arg));
  	arg.since = j64 - min(j64, j5mins);
  	ata_ering_map(&dev->ering, speed_down_verdict_cb, &arg);
  
  	if (arg.nr_errors[ATA_ECAT_DUBIOUS_ATA_BUS] +
  	    arg.nr_errors[ATA_ECAT_DUBIOUS_TOUT_HSM] > 1)
  		verdict |= ATA_EH_SPDN_SPEED_DOWN |
  			ATA_EH_SPDN_FALLBACK_TO_PIO | ATA_EH_SPDN_KEEP_ERRORS;
  
  	if (arg.nr_errors[ATA_ECAT_DUBIOUS_TOUT_HSM] +
  	    arg.nr_errors[ATA_ECAT_DUBIOUS_UNK_DEV] > 1)
  		verdict |= ATA_EH_SPDN_NCQ_OFF | ATA_EH_SPDN_KEEP_ERRORS;
  
  	if (arg.nr_errors[ATA_ECAT_ATA_BUS] +
  	    arg.nr_errors[ATA_ECAT_TOUT_HSM] +
  	    arg.nr_errors[ATA_ECAT_UNK_DEV] > 6)
  		verdict |= ATA_EH_SPDN_FALLBACK_TO_PIO;
  
  	/* scan past 10 mins of error history */
  	memset(&arg, 0, sizeof(arg));
  	arg.since = j64 - min(j64, j10mins);
  	ata_ering_map(&dev->ering, speed_down_verdict_cb, &arg);
  
  	if (arg.nr_errors[ATA_ECAT_TOUT_HSM] +
  	    arg.nr_errors[ATA_ECAT_UNK_DEV] > 3)
  		verdict |= ATA_EH_SPDN_NCQ_OFF;
  
  	if (arg.nr_errors[ATA_ECAT_ATA_BUS] +
  	    arg.nr_errors[ATA_ECAT_TOUT_HSM] > 3 ||
  	    arg.nr_errors[ATA_ECAT_UNK_DEV] > 6)
  		verdict |= ATA_EH_SPDN_SPEED_DOWN;
  
  	return verdict;
  }
  
  /**
   *	ata_eh_speed_down - record error and speed down if necessary
   *	@dev: Failed device
   *	@eflags: mask of ATA_EFLAG_* flags
   *	@err_mask: err_mask of the error
   *
   *	Record error and examine error history to determine whether
   *	adjusting transmission speed is necessary.  It also sets
   *	transmission limits appropriately if such adjustment is
   *	necessary.
   *
   *	LOCKING:
   *	Kernel thread context (may sleep).
   *
   *	RETURNS:
   *	Determined recovery action.
   */
  static unsigned int ata_eh_speed_down(struct ata_device *dev,
  				unsigned int eflags, unsigned int err_mask)
  {
  	struct ata_link *link = ata_dev_phys_link(dev);
  	int xfer_ok = 0;
  	unsigned int verdict;
  	unsigned int action = 0;
  
  	/* don't bother if Cat-0 error */
  	if (ata_eh_categorize_error(eflags, err_mask, &xfer_ok) == 0)
  		return 0;
  
  	/* record error and determine whether speed down is necessary */
  	ata_ering_record(&dev->ering, eflags, err_mask);
  	verdict = ata_eh_speed_down_verdict(dev);
  
  	/* turn off NCQ? */
  	if ((verdict & ATA_EH_SPDN_NCQ_OFF) &&
  	    (dev->flags & (ATA_DFLAG_PIO | ATA_DFLAG_NCQ |
  			   ATA_DFLAG_NCQ_OFF)) == ATA_DFLAG_NCQ) {
  		dev->flags |= ATA_DFLAG_NCQ_OFF;
  		ata_dev_warn(dev, "NCQ disabled due to excessive errors\n");
  		goto done;
  	}
  
  	/* speed down? */
  	if (verdict & ATA_EH_SPDN_SPEED_DOWN) {
  		/* speed down SATA link speed if possible */
  		if (sata_down_spd_limit(link, 0) == 0) {
  			action |= ATA_EH_RESET;
  			goto done;
  		}
  
  		/* lower transfer mode */
  		if (dev->spdn_cnt < 2) {
  			static const int dma_dnxfer_sel[] =
  				{ ATA_DNXFER_DMA, ATA_DNXFER_40C };
  			static const int pio_dnxfer_sel[] =
  				{ ATA_DNXFER_PIO, ATA_DNXFER_FORCE_PIO0 };
  			int sel;
  
  			if (dev->xfer_shift != ATA_SHIFT_PIO)
  				sel = dma_dnxfer_sel[dev->spdn_cnt];
  			else
  				sel = pio_dnxfer_sel[dev->spdn_cnt];
  
  			dev->spdn_cnt++;
  
  			if (ata_down_xfermask_limit(dev, sel) == 0) {
  				action |= ATA_EH_RESET;
  				goto done;
  			}
  		}
  	}
  
  	/* Fall back to PIO?  Slowing down to PIO is meaningless for
  	 * SATA ATA devices.  Consider it only for PATA and SATAPI.
  	 */
  	if ((verdict & ATA_EH_SPDN_FALLBACK_TO_PIO) && (dev->spdn_cnt >= 2) &&
  	    (link->ap->cbl != ATA_CBL_SATA || dev->class == ATA_DEV_ATAPI) &&
  	    (dev->xfer_shift != ATA_SHIFT_PIO)) {
  		if (ata_down_xfermask_limit(dev, ATA_DNXFER_FORCE_PIO) == 0) {
  			dev->spdn_cnt = 0;
  			action |= ATA_EH_RESET;
  			goto done;
  		}
  	}
  
  	return 0;
   done:
  	/* device has been slowed down, blow error history */
  	if (!(verdict & ATA_EH_SPDN_KEEP_ERRORS))
  		ata_ering_clear(&dev->ering);
  	return action;
  }
  
  /**
   *	ata_eh_link_autopsy - analyze error and determine recovery action
   *	@link: host link to perform autopsy on
   *
   *	Analyze why @link failed and determine which recovery actions
   *	are needed.  This function also sets more detailed AC_ERR_*
   *	values and fills sense data for ATAPI CHECK SENSE.
   *
   *	LOCKING:
   *	Kernel thread context (may sleep).
   */
  static void ata_eh_link_autopsy(struct ata_link *link)
  {
  	struct ata_port *ap = link->ap;
  	struct ata_eh_context *ehc = &link->eh_context;
  	struct ata_device *dev;
  	unsigned int all_err_mask = 0, eflags = 0;
  	int tag;
  	u32 serror;
  	int rc;
  
  	DPRINTK("ENTER\n");
  
  	if (ehc->i.flags & ATA_EHI_NO_AUTOPSY)
  		return;
  
  	/* obtain and analyze SError */
  	rc = sata_scr_read(link, SCR_ERROR, &serror);
  	if (rc == 0) {
  		ehc->i.serror |= serror;
  		ata_eh_analyze_serror(link);
  	} else if (rc != -EOPNOTSUPP) {
  		/* SError read failed, force reset and probing */
  		ehc->i.probe_mask |= ATA_ALL_DEVICES;
  		ehc->i.action |= ATA_EH_RESET;
  		ehc->i.err_mask |= AC_ERR_OTHER;
  	}
  
  	/* analyze NCQ failure */
  	ata_eh_analyze_ncq_error(link);
  
  	/* any real error trumps AC_ERR_OTHER */
  	if (ehc->i.err_mask & ~AC_ERR_OTHER)
  		ehc->i.err_mask &= ~AC_ERR_OTHER;
  
  	all_err_mask |= ehc->i.err_mask;
  
  	for (tag = 0; tag < ATA_MAX_QUEUE; tag++) {
  		struct ata_queued_cmd *qc = __ata_qc_from_tag(ap, tag);
  
  		if (!(qc->flags & ATA_QCFLAG_FAILED) ||
  		    ata_dev_phys_link(qc->dev) != link)
  			continue;
  
  		/* inherit upper level err_mask */
  		qc->err_mask |= ehc->i.err_mask;
  
  		/* analyze TF */
  		ehc->i.action |= ata_eh_analyze_tf(qc, &qc->result_tf);
  
  		/* DEV errors are probably spurious in case of ATA_BUS error */
  		if (qc->err_mask & AC_ERR_ATA_BUS)
  			qc->err_mask &= ~(AC_ERR_DEV | AC_ERR_MEDIA |
  					  AC_ERR_INVALID);
  
  		/* any real error trumps unknown error */
  		if (qc->err_mask & ~AC_ERR_OTHER)
  			qc->err_mask &= ~AC_ERR_OTHER;
  
  		/* SENSE_VALID trumps dev/unknown error and revalidation */
  		if (qc->flags & ATA_QCFLAG_SENSE_VALID)
  			qc->err_mask &= ~(AC_ERR_DEV | AC_ERR_OTHER);
  
  		/* determine whether the command is worth retrying */
  		if (qc->flags & ATA_QCFLAG_IO ||
  		    (!(qc->err_mask & AC_ERR_INVALID) &&
  		     qc->err_mask != AC_ERR_DEV))
  			qc->flags |= ATA_QCFLAG_RETRY;
  
  		/* accumulate error info */
  		ehc->i.dev = qc->dev;
  		all_err_mask |= qc->err_mask;
  		if (qc->flags & ATA_QCFLAG_IO)
  			eflags |= ATA_EFLAG_IS_IO;
  	}
  
  	/* enforce default EH actions */
  	if (ap->pflags & ATA_PFLAG_FROZEN ||
  	    all_err_mask & (AC_ERR_HSM | AC_ERR_TIMEOUT))
  		ehc->i.action |= ATA_EH_RESET;
  	else if (((eflags & ATA_EFLAG_IS_IO) && all_err_mask) ||
  		 (!(eflags & ATA_EFLAG_IS_IO) && (all_err_mask & ~AC_ERR_DEV)))
  		ehc->i.action |= ATA_EH_REVALIDATE;
  
  	/* If we have offending qcs and the associated failed device,
  	 * perform per-dev EH action only on the offending device.
  	 */
  	if (ehc->i.dev) {
  		ehc->i.dev_action[ehc->i.dev->devno] |=
  			ehc->i.action & ATA_EH_PERDEV_MASK;
  		ehc->i.action &= ~ATA_EH_PERDEV_MASK;
  	}
  
  	/* propagate timeout to host link */
  	if ((all_err_mask & AC_ERR_TIMEOUT) && !ata_is_host_link(link))
  		ap->link.eh_context.i.err_mask |= AC_ERR_TIMEOUT;
  
  	/* record error and consider speeding down */
  	dev = ehc->i.dev;
  	if (!dev && ((ata_link_max_devices(link) == 1 &&
  		      ata_dev_enabled(link->device))))
  	    dev = link->device;
  
  	if (dev) {
  		if (dev->flags & ATA_DFLAG_DUBIOUS_XFER)
  			eflags |= ATA_EFLAG_DUBIOUS_XFER;
  		ehc->i.action |= ata_eh_speed_down(dev, eflags, all_err_mask);
  	}
  
  	DPRINTK("EXIT\n");
  }
  
  /**
   *	ata_eh_autopsy - analyze error and determine recovery action
   *	@ap: host port to perform autopsy on
   *
   *	Analyze all links of @ap and determine why they failed and
   *	which recovery actions are needed.
   *
   *	LOCKING:
   *	Kernel thread context (may sleep).
   */
  void ata_eh_autopsy(struct ata_port *ap)
  {
  	struct ata_link *link;
  
  	ata_for_each_link(link, ap, EDGE)
  		ata_eh_link_autopsy(link);
  
  	/* Handle the frigging slave link.  Autopsy is done similarly
  	 * but actions and flags are transferred over to the master
  	 * link and handled from there.
  	 */
  	if (ap->slave_link) {
  		struct ata_eh_context *mehc = &ap->link.eh_context;
  		struct ata_eh_context *sehc = &ap->slave_link->eh_context;
  
  		/* transfer control flags from master to slave */
  		sehc->i.flags |= mehc->i.flags & ATA_EHI_TO_SLAVE_MASK;
  
  		/* perform autopsy on the slave link */
  		ata_eh_link_autopsy(ap->slave_link);
  
  		/* transfer actions from slave to master and clear slave */
  		ata_eh_about_to_do(ap->slave_link, NULL, ATA_EH_ALL_ACTIONS);
  		mehc->i.action		|= sehc->i.action;
  		mehc->i.dev_action[1]	|= sehc->i.dev_action[1];
  		mehc->i.flags		|= sehc->i.flags;
  		ata_eh_done(ap->slave_link, NULL, ATA_EH_ALL_ACTIONS);
  	}
  
  	/* Autopsy of fanout ports can affect host link autopsy.
  	 * Perform host link autopsy last.
  	 */
  	if (sata_pmp_attached(ap))
  		ata_eh_link_autopsy(&ap->link);
  }
  
  /**
   *	ata_get_cmd_descript - get description for ATA command
   *	@command: ATA command code to get description for
   *
   *	Return a textual description of the given command, or NULL if the
   *	command is not known.
   *
   *	LOCKING:
   *	None
   */
  const char *ata_get_cmd_descript(u8 command)
  {
  #ifdef CONFIG_ATA_VERBOSE_ERROR
  	static const struct
  	{
  		u8 command;
  		const char *text;
  	} cmd_descr[] = {
  		{ ATA_CMD_DEV_RESET,		"DEVICE RESET" },
  		{ ATA_CMD_CHK_POWER, 		"CHECK POWER MODE" },
  		{ ATA_CMD_STANDBY, 		"STANDBY" },
  		{ ATA_CMD_IDLE, 		"IDLE" },
  		{ ATA_CMD_EDD, 			"EXECUTE DEVICE DIAGNOSTIC" },
  		{ ATA_CMD_DOWNLOAD_MICRO,   	"DOWNLOAD MICROCODE" },
  		{ ATA_CMD_NOP,			"NOP" },
  		{ ATA_CMD_FLUSH, 		"FLUSH CACHE" },
  		{ ATA_CMD_FLUSH_EXT, 		"FLUSH CACHE EXT" },
  		{ ATA_CMD_ID_ATA,  		"IDENTIFY DEVICE" },
  		{ ATA_CMD_ID_ATAPI, 		"IDENTIFY PACKET DEVICE" },
  		{ ATA_CMD_SERVICE, 		"SERVICE" },
  		{ ATA_CMD_READ, 		"READ DMA" },
  		{ ATA_CMD_READ_EXT, 		"READ DMA EXT" },
  		{ ATA_CMD_READ_QUEUED, 		"READ DMA QUEUED" },
  		{ ATA_CMD_READ_STREAM_EXT, 	"READ STREAM EXT" },
  		{ ATA_CMD_READ_STREAM_DMA_EXT,  "READ STREAM DMA EXT" },
  		{ ATA_CMD_WRITE, 		"WRITE DMA" },
  		{ ATA_CMD_WRITE_EXT, 		"WRITE DMA EXT" },
  		{ ATA_CMD_WRITE_QUEUED, 	"WRITE DMA QUEUED EXT" },
  		{ ATA_CMD_WRITE_STREAM_EXT, 	"WRITE STREAM EXT" },
  		{ ATA_CMD_WRITE_STREAM_DMA_EXT, "WRITE STREAM DMA EXT" },
  		{ ATA_CMD_WRITE_FUA_EXT,	"WRITE DMA FUA EXT" },
  		{ ATA_CMD_WRITE_QUEUED_FUA_EXT, "WRITE DMA QUEUED FUA EXT" },
  		{ ATA_CMD_FPDMA_READ,		"READ FPDMA QUEUED" },
  		{ ATA_CMD_FPDMA_WRITE,		"WRITE FPDMA QUEUED" },
  		{ ATA_CMD_PIO_READ,		"READ SECTOR(S)" },
  		{ ATA_CMD_PIO_READ_EXT,		"READ SECTOR(S) EXT" },
  		{ ATA_CMD_PIO_WRITE,		"WRITE SECTOR(S)" },
  		{ ATA_CMD_PIO_WRITE_EXT,	"WRITE SECTOR(S) EXT" },
  		{ ATA_CMD_READ_MULTI,		"READ MULTIPLE" },
  		{ ATA_CMD_READ_MULTI_EXT,	"READ MULTIPLE EXT" },
  		{ ATA_CMD_WRITE_MULTI,		"WRITE MULTIPLE" },
  		{ ATA_CMD_WRITE_MULTI_EXT,	"WRITE MULTIPLE EXT" },
  		{ ATA_CMD_WRITE_MULTI_FUA_EXT, 	"WRITE MULTIPLE FUA EXT" },
  		{ ATA_CMD_SET_FEATURES,		"SET FEATURES" },
  		{ ATA_CMD_SET_MULTI,		"SET MULTIPLE MODE" },
  		{ ATA_CMD_VERIFY,		"READ VERIFY SECTOR(S)" },
  		{ ATA_CMD_VERIFY_EXT,		"READ VERIFY SECTOR(S) EXT" },
  		{ ATA_CMD_WRITE_UNCORR_EXT,	"WRITE UNCORRECTABLE EXT" },
  		{ ATA_CMD_STANDBYNOW1,		"STANDBY IMMEDIATE" },
  		{ ATA_CMD_IDLEIMMEDIATE,	"IDLE IMMEDIATE" },
  		{ ATA_CMD_SLEEP,		"SLEEP" },
  		{ ATA_CMD_INIT_DEV_PARAMS,	"INITIALIZE DEVICE PARAMETERS" },
  		{ ATA_CMD_READ_NATIVE_MAX,	"READ NATIVE MAX ADDRESS" },
  		{ ATA_CMD_READ_NATIVE_MAX_EXT,	"READ NATIVE MAX ADDRESS EXT" },
  		{ ATA_CMD_SET_MAX,		"SET MAX ADDRESS" },
  		{ ATA_CMD_SET_MAX_EXT,		"SET MAX ADDRESS EXT" },
  		{ ATA_CMD_READ_LOG_EXT,		"READ LOG EXT" },
  		{ ATA_CMD_WRITE_LOG_EXT,	"WRITE LOG EXT" },
  		{ ATA_CMD_READ_LOG_DMA_EXT,	"READ LOG DMA EXT" },
  		{ ATA_CMD_WRITE_LOG_DMA_EXT, 	"WRITE LOG DMA EXT" },
  		{ ATA_CMD_TRUSTED_RCV,		"TRUSTED RECEIVE" },
  		{ ATA_CMD_TRUSTED_RCV_DMA, 	"TRUSTED RECEIVE DMA" },
  		{ ATA_CMD_TRUSTED_SND,		"TRUSTED SEND" },
  		{ ATA_CMD_TRUSTED_SND_DMA, 	"TRUSTED SEND DMA" },
  		{ ATA_CMD_PMP_READ,		"READ BUFFER" },
  		{ ATA_CMD_PMP_WRITE,		"WRITE BUFFER" },
  		{ ATA_CMD_CONF_OVERLAY,		"DEVICE CONFIGURATION OVERLAY" },
  		{ ATA_CMD_SEC_SET_PASS,		"SECURITY SET PASSWORD" },
  		{ ATA_CMD_SEC_UNLOCK,		"SECURITY UNLOCK" },
  		{ ATA_CMD_SEC_ERASE_PREP,	"SECURITY ERASE PREPARE" },
  		{ ATA_CMD_SEC_ERASE_UNIT,	"SECURITY ERASE UNIT" },
  		{ ATA_CMD_SEC_FREEZE_LOCK,	"SECURITY FREEZE LOCK" },
  		{ ATA_CMD_SEC_DISABLE_PASS,	"SECURITY DISABLE PASSWORD" },
  		{ ATA_CMD_CONFIG_STREAM,	"CONFIGURE STREAM" },
  		{ ATA_CMD_SMART,		"SMART" },
  		{ ATA_CMD_MEDIA_LOCK,		"DOOR LOCK" },
  		{ ATA_CMD_MEDIA_UNLOCK,		"DOOR UNLOCK" },
  		{ ATA_CMD_DSM,			"DATA SET MANAGEMENT" },
  		{ ATA_CMD_CHK_MED_CRD_TYP, 	"CHECK MEDIA CARD TYPE" },
  		{ ATA_CMD_CFA_REQ_EXT_ERR, 	"CFA REQUEST EXTENDED ERROR" },
  		{ ATA_CMD_CFA_WRITE_NE,		"CFA WRITE SECTORS WITHOUT ERASE" },
  		{ ATA_CMD_CFA_TRANS_SECT,	"CFA TRANSLATE SECTOR" },
  		{ ATA_CMD_CFA_ERASE,		"CFA ERASE SECTORS" },
  		{ ATA_CMD_CFA_WRITE_MULT_NE, 	"CFA WRITE MULTIPLE WITHOUT ERASE" },
  		{ ATA_CMD_READ_LONG,		"READ LONG (with retries)" },
  		{ ATA_CMD_READ_LONG_ONCE,	"READ LONG (without retries)" },
  		{ ATA_CMD_WRITE_LONG,		"WRITE LONG (with retries)" },
  		{ ATA_CMD_WRITE_LONG_ONCE,	"WRITE LONG (without retries)" },
  		{ ATA_CMD_RESTORE,		"RECALIBRATE" },
  		{ 0,				NULL } /* terminate list */
  	};
  
  	unsigned int i;
  	for (i = 0; cmd_descr[i].text; i++)
  		if (cmd_descr[i].command == command)
  			return cmd_descr[i].text;
  #endif
  
  	return NULL;
  }
  
  /**
   *	ata_eh_link_report - report error handling to user
   *	@link: ATA link EH is going on
   *
   *	Report EH to user.
   *
   *	LOCKING:
   *	None.
   */
  static void ata_eh_link_report(struct ata_link *link)
  {
  	struct ata_port *ap = link->ap;
  	struct ata_eh_context *ehc = &link->eh_context;
  	const char *frozen, *desc;
  	char tries_buf[6];
  	int tag, nr_failed = 0;
  
  	if (ehc->i.flags & ATA_EHI_QUIET)
  		return;
  
  	desc = NULL;
  	if (ehc->i.desc[0] != '\0')
  		desc = ehc->i.desc;
  
  	for (tag = 0; tag < ATA_MAX_QUEUE; tag++) {
  		struct ata_queued_cmd *qc = __ata_qc_from_tag(ap, tag);
  
  		if (!(qc->flags & ATA_QCFLAG_FAILED) ||
  		    ata_dev_phys_link(qc->dev) != link ||
  		    ((qc->flags & ATA_QCFLAG_QUIET) &&
  		     qc->err_mask == AC_ERR_DEV))
  			continue;
  		if (qc->flags & ATA_QCFLAG_SENSE_VALID && !qc->err_mask)
  			continue;
  
  		nr_failed++;
  	}
  
  	if (!nr_failed && !ehc->i.err_mask)
  		return;
  
  	frozen = "";
  	if (ap->pflags & ATA_PFLAG_FROZEN)
  		frozen = " frozen";
  
  	memset(tries_buf, 0, sizeof(tries_buf));
  	if (ap->eh_tries < ATA_EH_MAX_TRIES)
  		snprintf(tries_buf, sizeof(tries_buf) - 1, " t%d",
  			 ap->eh_tries);
  
  	if (ehc->i.dev) {
  		ata_dev_err(ehc->i.dev, "exception Emask 0x%x "
  			    "SAct 0x%x SErr 0x%x action 0x%x%s%s\n",
  			    ehc->i.err_mask, link->sactive, ehc->i.serror,
  			    ehc->i.action, frozen, tries_buf);
  		if (desc)
  			ata_dev_err(ehc->i.dev, "%s\n", desc);
  	} else {
  		ata_link_err(link, "exception Emask 0x%x "
  			     "SAct 0x%x SErr 0x%x action 0x%x%s%s\n",
  			     ehc->i.err_mask, link->sactive, ehc->i.serror,
  			     ehc->i.action, frozen, tries_buf);
  		if (desc)
  			ata_link_err(link, "%s\n", desc);
  	}
  
  #ifdef CONFIG_ATA_VERBOSE_ERROR
  	if (ehc->i.serror)
  		ata_link_err(link,
  		  "SError: { %s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s}\n",
  		  ehc->i.serror & SERR_DATA_RECOVERED ? "RecovData " : "",
  		  ehc->i.serror & SERR_COMM_RECOVERED ? "RecovComm " : "",
  		  ehc->i.serror & SERR_DATA ? "UnrecovData " : "",
  		  ehc->i.serror & SERR_PERSISTENT ? "Persist " : "",
  		  ehc->i.serror & SERR_PROTOCOL ? "Proto " : "",
  		  ehc->i.serror & SERR_INTERNAL ? "HostInt " : "",
  		  ehc->i.serror & SERR_PHYRDY_CHG ? "PHYRdyChg " : "",
  		  ehc->i.serror & SERR_PHY_INT_ERR ? "PHYInt " : "",
  		  ehc->i.serror & SERR_COMM_WAKE ? "CommWake " : "",
  		  ehc->i.serror & SERR_10B_8B_ERR ? "10B8B " : "",
  		  ehc->i.serror & SERR_DISPARITY ? "Dispar " : "",
  		  ehc->i.serror & SERR_CRC ? "BadCRC " : "",
  		  ehc->i.serror & SERR_HANDSHAKE ? "Handshk " : "",
  		  ehc->i.serror & SERR_LINK_SEQ_ERR ? "LinkSeq " : "",
  		  ehc->i.serror & SERR_TRANS_ST_ERROR ? "TrStaTrns " : "",
  		  ehc->i.serror & SERR_UNRECOG_FIS ? "UnrecFIS " : "",
  		  ehc->i.serror & SERR_DEV_XCHG ? "DevExch " : "");
  #endif
  
  	for (tag = 0; tag < ATA_MAX_QUEUE; tag++) {
  		struct ata_queued_cmd *qc = __ata_qc_from_tag(ap, tag);
  		struct ata_taskfile *cmd = &qc->tf, *res = &qc->result_tf;
  		const u8 *cdb = qc->cdb;
  		char data_buf[20] = "";
  		char cdb_buf[70] = "";
  
  		if (!(qc->flags & ATA_QCFLAG_FAILED) ||
  		    ata_dev_phys_link(qc->dev) != link || !qc->err_mask)
  			continue;
  
  		if (qc->dma_dir != DMA_NONE) {
  			static const char *dma_str[] = {
  				[DMA_BIDIRECTIONAL]	= "bidi",
  				[DMA_TO_DEVICE]		= "out",
  				[DMA_FROM_DEVICE]	= "in",
  			};
  			static const char *prot_str[] = {
  				[ATA_PROT_PIO]		= "pio",
  				[ATA_PROT_DMA]		= "dma",
  				[ATA_PROT_NCQ]		= "ncq",
  				[ATAPI_PROT_PIO]	= "pio",
  				[ATAPI_PROT_DMA]	= "dma",
  			};
  
  			snprintf(data_buf, sizeof(data_buf), " %s %u %s",
  				 prot_str[qc->tf.protocol], qc->nbytes,
  				 dma_str[qc->dma_dir]);
  		}
  
  		if (ata_is_atapi(qc->tf.protocol)) {
  			if (qc->scsicmd)
  				scsi_print_command(qc->scsicmd);
  			else
  				snprintf(cdb_buf, sizeof(cdb_buf),
  				 "cdb %02x %02x %02x %02x %02x %02x %02x %02x  "
  				 "%02x %02x %02x %02x %02x %02x %02x %02x\n         ",
  				 cdb[0], cdb[1], cdb[2], cdb[3],
  				 cdb[4], cdb[5], cdb[6], cdb[7],
  				 cdb[8], cdb[9], cdb[10], cdb[11],
  				 cdb[12], cdb[13], cdb[14], cdb[15]);
  		} else {
  			const char *descr = ata_get_cmd_descript(cmd->command);
  			if (descr)
  				ata_dev_err(qc->dev, "failed command: %s\n",
  					    descr);
  		}
  
  		ata_dev_err(qc->dev,
  			"cmd %02x/%02x:%02x:%02x:%02x:%02x/%02x:%02x:%02x:%02x:%02x/%02x "
  			"tag %d%s\n         %s"
  			"res %02x/%02x:%02x:%02x:%02x:%02x/%02x:%02x:%02x:%02x:%02x/%02x "
  			"Emask 0x%x (%s)%s\n",
  			cmd->command, cmd->feature, cmd->nsect,
  			cmd->lbal, cmd->lbam, cmd->lbah,
  			cmd->hob_feature, cmd->hob_nsect,
  			cmd->hob_lbal, cmd->hob_lbam, cmd->hob_lbah,
  			cmd->device, qc->tag, data_buf, cdb_buf,
  			res->command, res->feature, res->nsect,
  			res->lbal, res->lbam, res->lbah,
  			res->hob_feature, res->hob_nsect,
  			res->hob_lbal, res->hob_lbam, res->hob_lbah,
  			res->device, qc->err_mask, ata_err_string(qc->err_mask),
  			qc->err_mask & AC_ERR_NCQ ? " <F>" : "");
  
  #ifdef CONFIG_ATA_VERBOSE_ERROR
  		if (res->command & (ATA_BUSY | ATA_DRDY | ATA_DF | ATA_DRQ |
  				    ATA_ERR)) {
  			if (res->command & ATA_BUSY)
  				ata_dev_err(qc->dev, "status: { Busy }\n");
  			else
  				ata_dev_err(qc->dev, "status: { %s%s%s%s}\n",
  				  res->command & ATA_DRDY ? "DRDY " : "",
  				  res->command & ATA_DF ? "DF " : "",
  				  res->command & ATA_DRQ ? "DRQ " : "",
  				  res->command & ATA_ERR ? "ERR " : "");
  		}
  
  		if (cmd->command != ATA_CMD_PACKET &&
  		    (res->feature & (ATA_ICRC | ATA_UNC | ATA_IDNF |
  				     ATA_ABORTED)))
  			ata_dev_err(qc->dev, "error: { %s%s%s%s}\n",
  			  res->feature & ATA_ICRC ? "ICRC " : "",
  			  res->feature & ATA_UNC ? "UNC " : "",
  			  res->feature & ATA_IDNF ? "IDNF " : "",
  			  res->feature & ATA_ABORTED ? "ABRT " : "");
  #endif
  	}
  }
  
  /**
   *	ata_eh_report - report error handling to user
   *	@ap: ATA port to report EH about
   *
   *	Report EH to user.
   *
   *	LOCKING:
   *	None.
   */
  void ata_eh_report(struct ata_port *ap)
  {
  	struct ata_link *link;
  
  	ata_for_each_link(link, ap, HOST_FIRST)
  		ata_eh_link_report(link);
  }
  
  static int ata_do_reset(struct ata_link *link, ata_reset_fn_t reset,
  			unsigned int *classes, unsigned long deadline,
  			bool clear_classes)
  {
  	struct ata_device *dev;
  
  	if (clear_classes)
  		ata_for_each_dev(dev, link, ALL)
  			classes[dev->devno] = ATA_DEV_UNKNOWN;
  
  	return reset(link, classes, deadline);
  }
  
  static int ata_eh_followup_srst_needed(struct ata_link *link, int rc)
  {
  	if ((link->flags & ATA_LFLAG_NO_SRST) || ata_link_offline(link))
  		return 0;
  	if (rc == -EAGAIN)
  		return 1;
  	if (sata_pmp_supported(link->ap) && ata_is_host_link(link))
  		return 1;
  	return 0;
  }
  
  int ata_eh_reset(struct ata_link *link, int classify,
  		 ata_prereset_fn_t prereset, ata_reset_fn_t softreset,
  		 ata_reset_fn_t hardreset, ata_postreset_fn_t postreset)
  {
  	struct ata_port *ap = link->ap;
  	struct ata_link *slave = ap->slave_link;
  	struct ata_eh_context *ehc = &link->eh_context;
  	struct ata_eh_context *sehc = slave ? &slave->eh_context : NULL;
  	unsigned int *classes = ehc->classes;
  	unsigned int lflags = link->flags;
  	int verbose = !(ehc->i.flags & ATA_EHI_QUIET);
  	int max_tries = 0, try = 0;
  	struct ata_link *failed_link;
  	struct ata_device *dev;
  	unsigned long deadline, now;
  	ata_reset_fn_t reset;
  	unsigned long flags;
  	u32 sstatus;
  	int nr_unknown, rc;
  
  	/*
  	 * Prepare to reset
  	 */
  	while (ata_eh_reset_timeouts[max_tries] != ULONG_MAX)
  		max_tries++;
  	if (link->flags & ATA_LFLAG_NO_HRST)
  		hardreset = NULL;
  	if (link->flags & ATA_LFLAG_NO_SRST)
  		softreset = NULL;
  
  	/* make sure each reset attempt is at least COOL_DOWN apart */
  	if (ehc->i.flags & ATA_EHI_DID_RESET) {
  		now = jiffies;
  		WARN_ON(time_after(ehc->last_reset, now));
  		deadline = ata_deadline(ehc->last_reset,
  					ATA_EH_RESET_COOL_DOWN);
  		if (time_before(now, deadline))
  			schedule_timeout_uninterruptible(deadline - now);
  	}
  
  	spin_lock_irqsave(ap->lock, flags);
  	ap->pflags |= ATA_PFLAG_RESETTING;
  	spin_unlock_irqrestore(ap->lock, flags);
  
  	ata_eh_about_to_do(link, NULL, ATA_EH_RESET);
  
  	ata_for_each_dev(dev, link, ALL) {
  		/* If we issue an SRST then an ATA drive (not ATAPI)
  		 * may change configuration and be in PIO0 timing. If
  		 * we do a hard reset (or are coming from power on)
  		 * this is true for ATA or ATAPI. Until we've set a
  		 * suitable controller mode we should not touch the
  		 * bus as we may be talking too fast.
  		 */
  		dev->pio_mode = XFER_PIO_0;
  
  		/* If the controller has a pio mode setup function
  		 * then use it to set the chipset to rights. Don't
  		 * touch the DMA setup as that will be dealt with when
  		 * configuring devices.
  		 */
  		if (ap->ops->set_piomode)
  			ap->ops->set_piomode(ap, dev);
  	}
  
  	/* prefer hardreset */
  	reset = NULL;
  	ehc->i.action &= ~ATA_EH_RESET;
  	if (hardreset) {
  		reset = hardreset;
  		ehc->i.action |= ATA_EH_HARDRESET;
  	} else if (softreset) {
  		reset = softreset;
  		ehc->i.action |= ATA_EH_SOFTRESET;
  	}
  
  	if (prereset) {
  		unsigned long deadline = ata_deadline(jiffies,
  						      ATA_EH_PRERESET_TIMEOUT);
  
  		if (slave) {
  			sehc->i.action &= ~ATA_EH_RESET;
  			sehc->i.action |= ehc->i.action;
  		}
  
  		rc = prereset(link, deadline);
  
  		/* If present, do prereset on slave link too.  Reset
  		 * is skipped iff both master and slave links report
  		 * -ENOENT or clear ATA_EH_RESET.
  		 */
  		if (slave && (rc == 0 || rc == -ENOENT)) {
  			int tmp;
  
  			tmp = prereset(slave, deadline);
  			if (tmp != -ENOENT)
  				rc = tmp;
  
  			ehc->i.action |= sehc->i.action;
  		}
  
  		if (rc) {
  			if (rc == -ENOENT) {
  				ata_link_dbg(link, "port disabled--ignoring\n");
  				ehc->i.action &= ~ATA_EH_RESET;
  
  				ata_for_each_dev(dev, link, ALL)
  					classes[dev->devno] = ATA_DEV_NONE;
  
  				rc = 0;
  			} else
  				ata_link_err(link,
  					     "prereset failed (errno=%d)\n",
  					     rc);
  			goto out;
  		}
  
  		/* prereset() might have cleared ATA_EH_RESET.  If so,
  		 * bang classes, thaw and return.
  		 */
  		if (reset && !(ehc->i.action & ATA_EH_RESET)) {
  			ata_for_each_dev(dev, link, ALL)
  				classes[dev->devno] = ATA_DEV_NONE;
  			if ((ap->pflags & ATA_PFLAG_FROZEN) &&
  			    ata_is_host_link(link))
  				ata_eh_thaw_port(ap);
  			rc = 0;
  			goto out;
  		}
  	}
  
   retry:
  	/*
  	 * Perform reset
  	 */
  	if (ata_is_host_link(link))
  		ata_eh_freeze_port(ap);
  
  	deadline = ata_deadline(jiffies, ata_eh_reset_timeouts[try++]);
  
  	if (reset) {
  		if (verbose)
  			ata_link_info(link, "%s resetting link\n",
  				      reset == softreset ? "soft" : "hard");
  
  		/* mark that this EH session started with reset */
  		ehc->last_reset = jiffies;
  		if (reset == hardreset)
  			ehc->i.flags |= ATA_EHI_DID_HARDRESET;
  		else
  			ehc->i.flags |= ATA_EHI_DID_SOFTRESET;
  
  		rc = ata_do_reset(link, reset, classes, deadline, true);
  		if (rc && rc != -EAGAIN) {
  			failed_link = link;
  			goto fail;
  		}
  
  		/* hardreset slave link if existent */
  		if (slave && reset == hardreset) {
  			int tmp;
  
  			if (verbose)
  				ata_link_info(slave, "hard resetting link\n");
  
  			ata_eh_about_to_do(slave, NULL, ATA_EH_RESET);
  			tmp = ata_do_reset(slave, reset, classes, deadline,
  					   false);
  			switch (tmp) {
  			case -EAGAIN:
  				rc = -EAGAIN;
  			case 0:
  				break;
  			default:
  				failed_link = slave;
  				rc = tmp;
  				goto fail;
  			}
  		}
  
  		/* perform follow-up SRST if necessary */
  		if (reset == hardreset &&
  		    ata_eh_followup_srst_needed(link, rc)) {
  			reset = softreset;
  
  			if (!reset) {
  				ata_link_err(link,
  	     "follow-up softreset required but no softreset available\n");
  				failed_link = link;
  				rc = -EINVAL;
  				goto fail;
  			}
  
  			ata_eh_about_to_do(link, NULL, ATA_EH_RESET);
  			rc = ata_do_reset(link, reset, classes, deadline, true);
  			if (rc) {
  				failed_link = link;
  				goto fail;
  			}
  		}
  	} else {
  		if (verbose)
  			ata_link_info(link,
  	"no reset method available, skipping reset\n");
  		if (!(lflags & ATA_LFLAG_ASSUME_CLASS))
  			lflags |= ATA_LFLAG_ASSUME_ATA;
  	}
  
  	/*
  	 * Post-reset processing
  	 */
  	ata_for_each_dev(dev, link, ALL) {
  		/* After the reset, the device state is PIO 0 and the
  		 * controller state is undefined.  Reset also wakes up
  		 * drives from sleeping mode.
  		 */
  		dev->pio_mode = XFER_PIO_0;
  		dev->flags &= ~ATA_DFLAG_SLEEPING;
  
  		if (ata_phys_link_offline(ata_dev_phys_link(dev)))
  			continue;
  
  		/* apply class override */
  		if (lflags & ATA_LFLAG_ASSUME_ATA)
  			classes[dev->devno] = ATA_DEV_ATA;
  		else if (lflags & ATA_LFLAG_ASSUME_SEMB)
  			classes[dev->devno] = ATA_DEV_SEMB_UNSUP;
  	}
  
  	/* record current link speed */
  	if (sata_scr_read(link, SCR_STATUS, &sstatus) == 0)
  		link->sata_spd = (sstatus >> 4) & 0xf;
  	if (slave && sata_scr_read(slave, SCR_STATUS, &sstatus) == 0)
  		slave->sata_spd = (sstatus >> 4) & 0xf;
  
  	/* thaw the port */
  	if (ata_is_host_link(link))
  		ata_eh_thaw_port(ap);
  
  	/* postreset() should clear hardware SError.  Although SError
  	 * is cleared during link resume, clearing SError here is
  	 * necessary as some PHYs raise hotplug events after SRST.
  	 * This introduces race condition where hotplug occurs between
  	 * reset and here.  This race is mediated by cross checking
  	 * link onlineness and classification result later.
  	 */
  	if (postreset) {
  		postreset(link, classes);
  		if (slave)
  			postreset(slave, classes);
  	}
  
  	/*
  	 * Some controllers can't be frozen very well and may set spurious
  	 * error conditions during reset.  Clear accumulated error
  	 * information and re-thaw the port if frozen.  As reset is the
  	 * final recovery action and we cross check link onlineness against
  	 * device classification later, no hotplug event is lost by this.
  	 */
  	spin_lock_irqsave(link->ap->lock, flags);
  	memset(&link->eh_info, 0, sizeof(link->eh_info));
  	if (slave)
  		memset(&slave->eh_info, 0, sizeof(link->eh_info));
  	ap->pflags &= ~ATA_PFLAG_EH_PENDING;
  	spin_unlock_irqrestore(link->ap->lock, flags);
  
  	if (ap->pflags & ATA_PFLAG_FROZEN)
  		ata_eh_thaw_port(ap);
  
  	/*
  	 * Make sure onlineness and classification result correspond.
  	 * Hotplug could have happened during reset and some
  	 * controllers fail to wait while a drive is spinning up after
  	 * being hotplugged causing misdetection.  By cross checking
  	 * link on/offlineness and classification result, those
  	 * conditions can be reliably detected and retried.
  	 */
  	nr_unknown = 0;
  	ata_for_each_dev(dev, link, ALL) {
  		if (ata_phys_link_online(ata_dev_phys_link(dev))) {
  			if (classes[dev->devno] == ATA_DEV_UNKNOWN) {
  				ata_dev_dbg(dev, "link online but device misclassified\n");
  				classes[dev->devno] = ATA_DEV_NONE;
  				nr_unknown++;
  			}
  		} else if (ata_phys_link_offline(ata_dev_phys_link(dev))) {
  			if (ata_class_enabled(classes[dev->devno]))
  				ata_dev_dbg(dev,
  					    "link offline, clearing class %d to NONE\n",
  					    classes[dev->devno]);
  			classes[dev->devno] = ATA_DEV_NONE;
  		} else if (classes[dev->devno] == ATA_DEV_UNKNOWN) {
  			ata_dev_dbg(dev,
  				    "link status unknown, clearing UNKNOWN to NONE\n");
  			classes[dev->devno] = ATA_DEV_NONE;
  		}
  	}
  
  	if (classify && nr_unknown) {
  		if (try < max_tries) {
  			ata_link_warn(link,
  				      "link online but %d devices misclassified, retrying\n",
  				      nr_unknown);
  			failed_link = link;
  			rc = -EAGAIN;
  			goto fail;
  		}
  		ata_link_warn(link,
  			      "link online but %d devices misclassified, "
  			      "device detection might fail\n", nr_unknown);
  	}
  
  	/* reset successful, schedule revalidation */
  	ata_eh_done(link, NULL, ATA_EH_RESET);
  	if (slave)
  		ata_eh_done(slave, NULL, ATA_EH_RESET);
  	ehc->last_reset = jiffies;		/* update to completion time */
  	ehc->i.action |= ATA_EH_REVALIDATE;
  	link->lpm_policy = ATA_LPM_UNKNOWN;	/* reset LPM state */
  
  	rc = 0;
   out:
  	/* clear hotplug flag */
  	ehc->i.flags &= ~ATA_EHI_HOTPLUGGED;
  	if (slave)
  		sehc->i.flags &= ~ATA_EHI_HOTPLUGGED;
  
  	spin_lock_irqsave(ap->lock, flags);
  	ap->pflags &= ~ATA_PFLAG_RESETTING;
  	spin_unlock_irqrestore(ap->lock, flags);
  
  	return rc;
  
   fail:
  	/* if SCR isn't accessible on a fan-out port, PMP needs to be reset */
  	if (!ata_is_host_link(link) &&
  	    sata_scr_read(link, SCR_STATUS, &sstatus))
  		rc = -ERESTART;
  
  	if (try >= max_tries) {
  		/*
  		 * Thaw host port even if reset failed, so that the port
  		 * can be retried on the next phy event.  This risks
  		 * repeated EH runs but seems to be a better tradeoff than
  		 * shutting down a port after a botched hotplug attempt.
  		 */
  		if (ata_is_host_link(link))
  			ata_eh_thaw_port(ap);
  		goto out;
  	}
  
  	now = jiffies;
  	if (time_before(now, deadline)) {
  		unsigned long delta = deadline - now;
  
  		ata_link_warn(failed_link,
  			"reset failed (errno=%d), retrying in %u secs\n",
  			rc, DIV_ROUND_UP(jiffies_to_msecs(delta), 1000));
  
  		ata_eh_release(ap);
  		while (delta)
  			delta = schedule_timeout_uninterruptible(delta);
  		ata_eh_acquire(ap);
  	}
  
  	/*
  	 * While disks spinup behind PMP, some controllers fail sending SRST.
  	 * They need to be reset - as well as the PMP - before retrying.
  	 */
  	if (rc == -ERESTART) {
  		if (ata_is_host_link(link))
  			ata_eh_thaw_port(ap);
  		goto out;
  	}
  
  	if (try == max_tries - 1) {
  		sata_down_spd_limit(link, 0);
  		if (slave)
  			sata_down_spd_limit(slave, 0);
  	} else if (rc == -EPIPE)
  		sata_down_spd_limit(failed_link, 0);
  
  	if (hardreset)
  		reset = hardreset;
  	goto retry;
  }
  
  static inline void ata_eh_pull_park_action(struct ata_port *ap)
  {
  	struct ata_link *link;
  	struct ata_device *dev;
  	unsigned long flags;
  
  	/*
  	 * This function can be thought of as an extended version of
  	 * ata_eh_about_to_do() specially crafted to accommodate the
  	 * requirements of ATA_EH_PARK handling. Since the EH thread
  	 * does not leave the do {} while () loop in ata_eh_recover as
  	 * long as the timeout for a park request to *one* device on
  	 * the port has not expired, and since we still want to pick
  	 * up park requests to other devices on the same port or
  	 * timeout updates for the same device, we have to pull
  	 * ATA_EH_PARK actions from eh_info into eh_context.i
  	 * ourselves at the beginning of each pass over the loop.
  	 *
  	 * Additionally, all write accesses to &ap->park_req_pending
  	 * through INIT_COMPLETION() (see below) or complete_all()
  	 * (see ata_scsi_park_store()) are protected by the host lock.
  	 * As a result we have that park_req_pending.done is zero on
  	 * exit from this function, i.e. when ATA_EH_PARK actions for
  	 * *all* devices on port ap have been pulled into the
  	 * respective eh_context structs. If, and only if,
  	 * park_req_pending.done is non-zero by the time we reach
  	 * wait_for_completion_timeout(), another ATA_EH_PARK action
  	 * has been scheduled for at least one of the devices on port
  	 * ap and we have to cycle over the do {} while () loop in
  	 * ata_eh_recover() again.
  	 */
  
  	spin_lock_irqsave(ap->lock, flags);
  	INIT_COMPLETION(ap->park_req_pending);
  	ata_for_each_link(link, ap, EDGE) {
  		ata_for_each_dev(dev, link, ALL) {
  			struct ata_eh_info *ehi = &link->eh_info;
  
  			link->eh_context.i.dev_action[dev->devno] |=
  				ehi->dev_action[dev->devno] & ATA_EH_PARK;
  			ata_eh_clear_action(link, dev, ehi, ATA_EH_PARK);
  		}
  	}
  	spin_unlock_irqrestore(ap->lock, flags);
  }
  
  static void ata_eh_park_issue_cmd(struct ata_device *dev, int park)
  {
  	struct ata_eh_context *ehc = &dev->link->eh_context;
  	struct ata_taskfile tf;
  	unsigned int err_mask;
  
  	ata_tf_init(dev, &tf);
  	if (park) {
  		ehc->unloaded_mask |= 1 << dev->devno;
  		tf.command = ATA_CMD_IDLEIMMEDIATE;
  		tf.feature = 0x44;
  		tf.lbal = 0x4c;
  		tf.lbam = 0x4e;
  		tf.lbah = 0x55;
  	} else {
  		ehc->unloaded_mask &= ~(1 << dev->devno);
  		tf.command = ATA_CMD_CHK_POWER;
  	}
  
  	tf.flags |= ATA_TFLAG_DEVICE | ATA_TFLAG_ISADDR;
  	tf.protocol |= ATA_PROT_NODATA;
  	err_mask = ata_exec_internal(dev, &tf, NULL, DMA_NONE, NULL, 0, 0);
  	if (park && (err_mask || tf.lbal != 0xc4)) {
  		ata_dev_err(dev, "head unload failed!\n");
  		ehc->unloaded_mask &= ~(1 << dev->devno);
  	}
  }
  
  static int ata_eh_revalidate_and_attach(struct ata_link *link,
  					struct ata_device **r_failed_dev)
  {
  	struct ata_port *ap = link->ap;
  	struct ata_eh_context *ehc = &link->eh_context;
  	struct ata_device *dev;
  	unsigned int new_mask = 0;
  	unsigned long flags;
  	int rc = 0;
  
  	DPRINTK("ENTER\n");
  
  	/* For PATA drive side cable detection to work, IDENTIFY must
  	 * be done backwards such that PDIAG- is released by the slave
  	 * device before the master device is identified.
  	 */
  	ata_for_each_dev(dev, link, ALL_REVERSE) {
  		unsigned int action = ata_eh_dev_action(dev);
  		unsigned int readid_flags = 0;
  
  		if (ehc->i.flags & ATA_EHI_DID_RESET)
  			readid_flags |= ATA_READID_POSTRESET;
  
  		if ((action & ATA_EH_REVALIDATE) && ata_dev_enabled(dev)) {
  			WARN_ON(dev->class == ATA_DEV_PMP);
  
  			if (ata_phys_link_offline(ata_dev_phys_link(dev))) {
  				rc = -EIO;
  				goto err;
  			}
  
  			ata_eh_about_to_do(link, dev, ATA_EH_REVALIDATE);
  			rc = ata_dev_revalidate(dev, ehc->classes[dev->devno],
  						readid_flags);
  			if (rc)
  				goto err;
  
  			ata_eh_done(link, dev, ATA_EH_REVALIDATE);
  
  			/* Configuration may have changed, reconfigure
  			 * transfer mode.
  			 */
  			ehc->i.flags |= ATA_EHI_SETMODE;
  
  			/* schedule the scsi_rescan_device() here */
  			schedule_work(&(ap->scsi_rescan_task));
  		} else if (dev->class == ATA_DEV_UNKNOWN &&
  			   ehc->tries[dev->devno] &&
  			   ata_class_enabled(ehc->classes[dev->devno])) {
  			/* Temporarily set dev->class, it will be
  			 * permanently set once all configurations are
  			 * complete.  This is necessary because new
  			 * device configuration is done in two
  			 * separate loops.
  			 */
  			dev->class = ehc->classes[dev->devno];
  
  			if (dev->class == ATA_DEV_PMP)
  				rc = sata_pmp_attach(dev);
  			else
  				rc = ata_dev_read_id(dev, &dev->class,
  						     readid_flags, dev->id);
  
  			/* read_id might have changed class, store and reset */
  			ehc->classes[dev->devno] = dev->class;
  			dev->class = ATA_DEV_UNKNOWN;
  
  			switch (rc) {
  			case 0:
  				/* clear error info accumulated during probe */
  				ata_ering_clear(&dev->ering);
  				new_mask |= 1 << dev->devno;
  				break;
  			case -ENOENT:
  				/* IDENTIFY was issued to non-existent
  				 * device.  No need to reset.  Just
  				 * thaw and ignore the device.
  				 */
  				ata_eh_thaw_port(ap);
  				break;
  			default:
  				goto err;
  			}
  		}
  	}
  
  	/* PDIAG- should have been released, ask cable type if post-reset */
  	if ((ehc->i.flags & ATA_EHI_DID_RESET) && ata_is_host_link(link)) {
  		if (ap->ops->cable_detect)
  			ap->cbl = ap->ops->cable_detect(ap);
  		ata_force_cbl(ap);
  	}
  
  	/* Configure new devices forward such that user doesn't see
  	 * device detection messages backwards.
  	 */
  	ata_for_each_dev(dev, link, ALL) {
  		if (!(new_mask & (1 << dev->devno)))
  			continue;
  
  		dev->class = ehc->classes[dev->devno];
  
  		if (dev->class == ATA_DEV_PMP)
  			continue;
  
  		ehc->i.flags |= ATA_EHI_PRINTINFO;
  		rc = ata_dev_configure(dev);
  		ehc->i.flags &= ~ATA_EHI_PRINTINFO;
  		if (rc) {
  			dev->class = ATA_DEV_UNKNOWN;
  			goto err;
  		}
  
  		spin_lock_irqsave(ap->lock, flags);
  		ap->pflags |= ATA_PFLAG_SCSI_HOTPLUG;
  		spin_unlock_irqrestore(ap->lock, flags);
  
  		/* new device discovered, configure xfermode */
  		ehc->i.flags |= ATA_EHI_SETMODE;
  	}
  
  	return 0;
  
   err:
  	*r_failed_dev = dev;
  	DPRINTK("EXIT rc=%d\n", rc);
  	return rc;
  }
  
  /**
   *	ata_set_mode - Program timings and issue SET FEATURES - XFER
   *	@link: link on which timings will be programmed
   *	@r_failed_dev: out parameter for failed device
   *
   *	Set ATA device disk transfer mode (PIO3, UDMA6, etc.).  If
   *	ata_set_mode() fails, pointer to the failing device is
   *	returned in @r_failed_dev.
   *
   *	LOCKING:
   *	PCI/etc. bus probe sem.
   *
   *	RETURNS:
   *	0 on success, negative errno otherwise
   */
  int ata_set_mode(struct ata_link *link, struct ata_device **r_failed_dev)
  {
  	struct ata_port *ap = link->ap;
  	struct ata_device *dev;
  	int rc;
  
  	/* if data transfer is verified, clear DUBIOUS_XFER on ering top */
  	ata_for_each_dev(dev, link, ENABLED) {
  		if (!(dev->flags & ATA_DFLAG_DUBIOUS_XFER)) {
  			struct ata_ering_entry *ent;
  
  			ent = ata_ering_top(&dev->ering);
  			if (ent)
  				ent->eflags &= ~ATA_EFLAG_DUBIOUS_XFER;
  		}
  	}
  
  	/* has private set_mode? */
  	if (ap->ops->set_mode)
  		rc = ap->ops->set_mode(link, r_failed_dev);
  	else
  		rc = ata_do_set_mode(link, r_failed_dev);
  
  	/* if transfer mode has changed, set DUBIOUS_XFER on device */
  	ata_for_each_dev(dev, link, ENABLED) {
  		struct ata_eh_context *ehc = &link->eh_context;
  		u8 saved_xfer_mode = ehc->saved_xfer_mode[dev->devno];
  		u8 saved_ncq = !!(ehc->saved_ncq_enabled & (1 << dev->devno));
  
  		if (dev->xfer_mode != saved_xfer_mode ||
  		    ata_ncq_enabled(dev) != saved_ncq)
  			dev->flags |= ATA_DFLAG_DUBIOUS_XFER;
  	}
  
  	return rc;
  }
  
  /**
   *	atapi_eh_clear_ua - Clear ATAPI UNIT ATTENTION after reset
   *	@dev: ATAPI device to clear UA for
   *
   *	Resets and other operations can make an ATAPI device raise
   *	UNIT ATTENTION which causes the next operation to fail.  This
   *	function clears UA.
   *
   *	LOCKING:
   *	EH context (may sleep).
   *
   *	RETURNS:
   *	0 on success, -errno on failure.
   */
  static int atapi_eh_clear_ua(struct ata_device *dev)
  {
  	int i;
  
  	for (i = 0; i < ATA_EH_UA_TRIES; i++) {
  		u8 *sense_buffer = dev->link->ap->sector_buf;
  		u8 sense_key = 0;
  		unsigned int err_mask;
  
  		err_mask = atapi_eh_tur(dev, &sense_key);
  		if (err_mask != 0 && err_mask != AC_ERR_DEV) {
  			ata_dev_warn(dev,
  				     "TEST_UNIT_READY failed (err_mask=0x%x)\n",
  				     err_mask);
  			return -EIO;
  		}
  
  		if (!err_mask || sense_key != UNIT_ATTENTION)
  			return 0;
  
  		err_mask = atapi_eh_request_sense(dev, sense_buffer, sense_key);
  		if (err_mask) {
  			ata_dev_warn(dev, "failed to clear "
  				"UNIT ATTENTION (err_mask=0x%x)\n", err_mask);
  			return -EIO;
  		}
  	}
  
  	ata_dev_warn(dev, "UNIT ATTENTION persists after %d tries\n",
  		     ATA_EH_UA_TRIES);
  
  	return 0;
  }
  
  /**
   *	ata_eh_maybe_retry_flush - Retry FLUSH if necessary
   *	@dev: ATA device which may need FLUSH retry
   *
   *	If @dev failed FLUSH, it needs to be reported upper layer
   *	immediately as it means that @dev failed to remap and already
   *	lost at least a sector and further FLUSH retrials won't make
   *	any difference to the lost sector.  However, if FLUSH failed
   *	for other reasons, for example transmission error, FLUSH needs
   *	to be retried.
   *
   *	This function determines whether FLUSH failure retry is
   *	necessary and performs it if so.
   *
   *	RETURNS:
   *	0 if EH can continue, -errno if EH needs to be repeated.
   */
  static int ata_eh_maybe_retry_flush(struct ata_device *dev)
  {
  	struct ata_link *link = dev->link;
  	struct ata_port *ap = link->ap;
  	struct ata_queued_cmd *qc;
  	struct ata_taskfile tf;
  	unsigned int err_mask;
  	int rc = 0;
  
  	/* did flush fail for this device? */
  	if (!ata_tag_valid(link->active_tag))
  		return 0;
  
  	qc = __ata_qc_from_tag(ap, link->active_tag);
  	if (qc->dev != dev || (qc->tf.command != ATA_CMD_FLUSH_EXT &&
  			       qc->tf.command != ATA_CMD_FLUSH))
  		return 0;
  
  	/* if the device failed it, it should be reported to upper layers */
  	if (qc->err_mask & AC_ERR_DEV)
  		return 0;
  
  	/* flush failed for some other reason, give it another shot */
  	ata_tf_init(dev, &tf);
  
  	tf.command = qc->tf.command;
  	tf.flags |= ATA_TFLAG_DEVICE;
  	tf.protocol = ATA_PROT_NODATA;
  
  	ata_dev_warn(dev, "retrying FLUSH 0x%x Emask 0x%x\n",
  		       tf.command, qc->err_mask);
  
  	err_mask = ata_exec_internal(dev, &tf, NULL, DMA_NONE, NULL, 0, 0);
  	if (!err_mask) {
  		/*
  		 * FLUSH is complete but there's no way to
  		 * successfully complete a failed command from EH.
  		 * Making sure retry is allowed at least once and
  		 * retrying it should do the trick - whatever was in
  		 * the cache is already on the platter and this won't
  		 * cause infinite loop.
  		 */
  		qc->scsicmd->allowed = max(qc->scsicmd->allowed, 1);
  	} else {
  		ata_dev_warn(dev, "FLUSH failed Emask 0x%x\n",
  			       err_mask);
  		rc = -EIO;
  
  		/* if device failed it, report it to upper layers */
  		if (err_mask & AC_ERR_DEV) {
  			qc->err_mask |= AC_ERR_DEV;
  			qc->result_tf = tf;
  			if (!(ap->pflags & ATA_PFLAG_FROZEN))
  				rc = 0;
  		}
  	}
  	return rc;
  }
  
  /**
   *	ata_eh_set_lpm - configure SATA interface power management
   *	@link: link to configure power management
   *	@policy: the link power management policy
   *	@r_failed_dev: out parameter for failed device
   *
   *	Enable SATA Interface power management.  This will enable
   *	Device Interface Power Management (DIPM) for min_power
   * 	policy, and then call driver specific callbacks for
   *	enabling Host Initiated Power management.
   *
   *	LOCKING:
   *	EH context.
   *
   *	RETURNS:
   *	0 on success, -errno on failure.
   */
  static int ata_eh_set_lpm(struct ata_link *link, enum ata_lpm_policy policy,
  			  struct ata_device **r_failed_dev)
  {
  	struct ata_port *ap = ata_is_host_link(link) ? link->ap : NULL;
  	struct ata_eh_context *ehc = &link->eh_context;
  	struct ata_device *dev, *link_dev = NULL, *lpm_dev = NULL;
  	enum ata_lpm_policy old_policy = link->lpm_policy;
  	bool no_dipm = link->ap->flags & ATA_FLAG_NO_DIPM;
  	unsigned int hints = ATA_LPM_EMPTY | ATA_LPM_HIPM;
  	unsigned int err_mask;
  	int rc;
  
  	/* if the link or host doesn't do LPM, noop */
  	if ((link->flags & ATA_LFLAG_NO_LPM) || (ap && !ap->ops->set_lpm))
  		return 0;
  
  	/*
  	 * DIPM is enabled only for MIN_POWER as some devices
  	 * misbehave when the host NACKs transition to SLUMBER.  Order
  	 * device and link configurations such that the host always
  	 * allows DIPM requests.
  	 */
  	ata_for_each_dev(dev, link, ENABLED) {
  		bool hipm = ata_id_has_hipm(dev->id);
  		bool dipm = ata_id_has_dipm(dev->id) && !no_dipm;
  
  		/* find the first enabled and LPM enabled devices */
  		if (!link_dev)
  			link_dev = dev;
  
  		if (!lpm_dev && (hipm || dipm))
  			lpm_dev = dev;
  
  		hints &= ~ATA_LPM_EMPTY;
  		if (!hipm)
  			hints &= ~ATA_LPM_HIPM;
  
  		/* disable DIPM before changing link config */
  		if (policy != ATA_LPM_MIN_POWER && dipm) {
  			err_mask = ata_dev_set_feature(dev,
  					SETFEATURES_SATA_DISABLE, SATA_DIPM);
  			if (err_mask && err_mask != AC_ERR_DEV) {
  				ata_dev_warn(dev,
  					     "failed to disable DIPM, Emask 0x%x\n",
  					     err_mask);
  				rc = -EIO;
  				goto fail;
  			}
  		}
  	}
  
  	if (ap) {
  		rc = ap->ops->set_lpm(link, policy, hints);
  		if (!rc && ap->slave_link)
  			rc = ap->ops->set_lpm(ap->slave_link, policy, hints);
  	} else
  		rc = sata_pmp_set_lpm(link, policy, hints);
  
  	/*
  	 * Attribute link config failure to the first (LPM) enabled
  	 * device on the link.
  	 */
  	if (rc) {
  		if (rc == -EOPNOTSUPP) {
  			link->flags |= ATA_LFLAG_NO_LPM;
  			return 0;
  		}
  		dev = lpm_dev ? lpm_dev : link_dev;
  		goto fail;
  	}
  
  	/*
  	 * Low level driver acked the transition.  Issue DIPM command
  	 * with the new policy set.
  	 */
  	link->lpm_policy = policy;
  	if (ap && ap->slave_link)
  		ap->slave_link->lpm_policy = policy;
  
  	/* host config updated, enable DIPM if transitioning to MIN_POWER */
  	ata_for_each_dev(dev, link, ENABLED) {
  		if (policy == ATA_LPM_MIN_POWER && !no_dipm &&
  		    ata_id_has_dipm(dev->id)) {
  			err_mask = ata_dev_set_feature(dev,
  					SETFEATURES_SATA_ENABLE, SATA_DIPM);
  			if (err_mask && err_mask != AC_ERR_DEV) {
  				ata_dev_warn(dev,
  					"failed to enable DIPM, Emask 0x%x\n",
  					err_mask);
  				rc = -EIO;
  				goto fail;
  			}
  		}
  	}
  
  	return 0;
  
  fail:
  	/* restore the old policy */
  	link->lpm_policy = old_policy;
  	if (ap && ap->slave_link)
  		ap->slave_link->lpm_policy = old_policy;
  
  	/* if no device or only one more chance is left, disable LPM */
  	if (!dev || ehc->tries[dev->devno] <= 2) {
  		ata_link_warn(link, "disabling LPM on the link\n");
  		link->flags |= ATA_LFLAG_NO_LPM;
  	}
  	if (r_failed_dev)
  		*r_failed_dev = dev;
  	return rc;
  }
  
  int ata_link_nr_enabled(struct ata_link *link)
  {
  	struct ata_device *dev;
  	int cnt = 0;
  
  	ata_for_each_dev(dev, link, ENABLED)
  		cnt++;
  	return cnt;
  }
  
  static int ata_link_nr_vacant(struct ata_link *link)
  {
  	struct ata_device *dev;
  	int cnt = 0;
  
  	ata_for_each_dev(dev, link, ALL)
  		if (dev->class == ATA_DEV_UNKNOWN)
  			cnt++;
  	return cnt;
  }
  
  static int ata_eh_skip_recovery(struct ata_link *link)
  {
  	struct ata_port *ap = link->ap;
  	struct ata_eh_context *ehc = &link->eh_context;
  	struct ata_device *dev;
  
  	/* skip disabled links */
  	if (link->flags & ATA_LFLAG_DISABLED)
  		return 1;
  
  	/* skip if explicitly requested */
  	if (ehc->i.flags & ATA_EHI_NO_RECOVERY)
  		return 1;
  
  	/* thaw frozen port and recover failed devices */
  	if ((ap->pflags & ATA_PFLAG_FROZEN) || ata_link_nr_enabled(link))
  		return 0;
  
  	/* reset at least once if reset is requested */
  	if ((ehc->i.action & ATA_EH_RESET) &&
  	    !(ehc->i.flags & ATA_EHI_DID_RESET))
  		return 0;
  
  	/* skip if class codes for all vacant slots are ATA_DEV_NONE */
  	ata_for_each_dev(dev, link, ALL) {
  		if (dev->class == ATA_DEV_UNKNOWN &&
  		    ehc->classes[dev->devno] != ATA_DEV_NONE)
  			return 0;
  	}
  
  	return 1;
  }
  
  static int ata_count_probe_trials_cb(struct ata_ering_entry *ent, void *void_arg)
  {
  	u64 interval = msecs_to_jiffies(ATA_EH_PROBE_TRIAL_INTERVAL);
  	u64 now = get_jiffies_64();
  	int *trials = void_arg;
  
  	if ((ent->eflags & ATA_EFLAG_OLD_ER) ||
  	    (ent->timestamp < now - min(now, interval)))
  		return -1;
  
  	(*trials)++;
  	return 0;
  }
  
  static int ata_eh_schedule_probe(struct ata_device *dev)
  {
  	struct ata_eh_context *ehc = &dev->link->eh_context;
  	struct ata_link *link = ata_dev_phys_link(dev);
  	int trials = 0;
  
  	if (!(ehc->i.probe_mask & (1 << dev->devno)) ||
  	    (ehc->did_probe_mask & (1 << dev->devno)))
  		return 0;
  
  	ata_eh_detach_dev(dev);
  	ata_dev_init(dev);
  	ehc->did_probe_mask |= (1 << dev->devno);
  	ehc->i.action |= ATA_EH_RESET;
  	ehc->saved_xfer_mode[dev->devno] = 0;
  	ehc->saved_ncq_enabled &= ~(1 << dev->devno);
  
  	/* the link maybe in a deep sleep, wake it up */
  	if (link->lpm_policy > ATA_LPM_MAX_POWER) {
  		if (ata_is_host_link(link))
  			link->ap->ops->set_lpm(link, ATA_LPM_MAX_POWER,
  					       ATA_LPM_EMPTY);
  		else
  			sata_pmp_set_lpm(link, ATA_LPM_MAX_POWER,
  					 ATA_LPM_EMPTY);
  	}
  
  	/* Record and count probe trials on the ering.  The specific
  	 * error mask used is irrelevant.  Because a successful device
  	 * detection clears the ering, this count accumulates only if
  	 * there are consecutive failed probes.
  	 *
  	 * If the count is equal to or higher than ATA_EH_PROBE_TRIALS
  	 * in the last ATA_EH_PROBE_TRIAL_INTERVAL, link speed is
  	 * forced to 1.5Gbps.
  	 *
  	 * This is to work around cases where failed link speed
  	 * negotiation results in device misdetection leading to
  	 * infinite DEVXCHG or PHRDY CHG events.
  	 */
  	ata_ering_record(&dev->ering, 0, AC_ERR_OTHER);
  	ata_ering_map(&dev->ering, ata_count_probe_trials_cb, &trials);
  
  	if (trials > ATA_EH_PROBE_TRIALS)
  		sata_down_spd_limit(link, 1);
  
  	return 1;
  }
  
  static int ata_eh_handle_dev_fail(struct ata_device *dev, int err)
  {
  	struct ata_eh_context *ehc = &dev->link->eh_context;
  
  	/* -EAGAIN from EH routine indicates retry without prejudice.
  	 * The requester is responsible for ensuring forward progress.
  	 */
  	if (err != -EAGAIN)
  		ehc->tries[dev->devno]--;
  
  	switch (err) {
  	case -ENODEV:
  		/* device missing or wrong IDENTIFY data, schedule probing */
  		ehc->i.probe_mask |= (1 << dev->devno);
  	case -EINVAL:
  		/* give it just one more chance */
  		ehc->tries[dev->devno] = min(ehc->tries[dev->devno], 1);
  	case -EIO:
  		if (ehc->tries[dev->devno] == 1) {
  			/* This is the last chance, better to slow
  			 * down than lose it.
  			 */
  			sata_down_spd_limit(ata_dev_phys_link(dev), 0);
  			if (dev->pio_mode > XFER_PIO_0)
  				ata_down_xfermask_limit(dev, ATA_DNXFER_PIO);
  		}
  	}
  
  	if (ata_dev_enabled(dev) && !ehc->tries[dev->devno]) {
  		/* disable device if it has used up all its chances */
  		ata_dev_disable(dev);
  
  		/* detach if offline */
  		if (ata_phys_link_offline(ata_dev_phys_link(dev)))
  			ata_eh_detach_dev(dev);
  
  		/* schedule probe if necessary */
  		if (ata_eh_schedule_probe(dev)) {
  			ehc->tries[dev->devno] = ATA_EH_DEV_TRIES;
  			memset(ehc->cmd_timeout_idx[dev->devno], 0,
  			       sizeof(ehc->cmd_timeout_idx[dev->devno]));
  		}
  
  		return 1;
  	} else {
  		ehc->i.action |= ATA_EH_RESET;
  		return 0;
  	}
  }
  
  /**
   *	ata_eh_recover - recover host port after error
   *	@ap: host port to recover
   *	@prereset: prereset method (can be NULL)
   *	@softreset: softreset method (can be NULL)
   *	@hardreset: hardreset method (can be NULL)
   *	@postreset: postreset method (can be NULL)
   *	@r_failed_link: out parameter for failed link
   *
   *	This is the alpha and omega, eum and yang, heart and soul of
   *	libata exception handling.  On entry, actions required to
   *	recover each link and hotplug requests are recorded in the
   *	link's eh_context.  This function executes all the operations
   *	with appropriate retrials and fallbacks to resurrect failed
   *	devices, detach goners and greet newcomers.
   *
   *	LOCKING:
   *	Kernel thread context (may sleep).
   *
   *	RETURNS:
   *	0 on success, -errno on failure.
   */
  int ata_eh_recover(struct ata_port *ap, ata_prereset_fn_t prereset,
  		   ata_reset_fn_t softreset, ata_reset_fn_t hardreset,
  		   ata_postreset_fn_t postreset,
  		   struct ata_link **r_failed_link)
  {
  	struct ata_link *link;
  	struct ata_device *dev;
  	int rc, nr_fails;
  	unsigned long flags, deadline;
  
  	DPRINTK("ENTER\n");
  
  	/* prep for recovery */
  	ata_for_each_link(link, ap, EDGE) {
  		struct ata_eh_context *ehc = &link->eh_context;
  
  		/* re-enable link? */
  		if (ehc->i.action & ATA_EH_ENABLE_LINK) {
  			ata_eh_about_to_do(link, NULL, ATA_EH_ENABLE_LINK);
  			spin_lock_irqsave(ap->lock, flags);
  			link->flags &= ~ATA_LFLAG_DISABLED;
  			spin_unlock_irqrestore(ap->lock, flags);
  			ata_eh_done(link, NULL, ATA_EH_ENABLE_LINK);
  		}
  
  		ata_for_each_dev(dev, link, ALL) {
  			if (link->flags & ATA_LFLAG_NO_RETRY)
  				ehc->tries[dev->devno] = 1;
  			else
  				ehc->tries[dev->devno] = ATA_EH_DEV_TRIES;
  
  			/* collect port action mask recorded in dev actions */
  			ehc->i.action |= ehc->i.dev_action[dev->devno] &
  					 ~ATA_EH_PERDEV_MASK;
  			ehc->i.dev_action[dev->devno] &= ATA_EH_PERDEV_MASK;
  
  			/* process hotplug request */
  			if (dev->flags & ATA_DFLAG_DETACH)
  				ata_eh_detach_dev(dev);
  
  			/* schedule probe if necessary */
  			if (!ata_dev_enabled(dev))
  				ata_eh_schedule_probe(dev);
  		}
  	}
  
   retry:
  	rc = 0;
  
  	/* if UNLOADING, finish immediately */
  	if (ap->pflags & ATA_PFLAG_UNLOADING)
  		goto out;
  
  	/* prep for EH */
  	ata_for_each_link(link, ap, EDGE) {
  		struct ata_eh_context *ehc = &link->eh_context;
  
  		/* skip EH if possible. */
  		if (ata_eh_skip_recovery(link))
  			ehc->i.action = 0;
  
  		ata_for_each_dev(dev, link, ALL)
  			ehc->classes[dev->devno] = ATA_DEV_UNKNOWN;
  	}
  
  	/* reset */
  	ata_for_each_link(link, ap, EDGE) {
  		struct ata_eh_context *ehc = &link->eh_context;
  
  		if (!(ehc->i.action & ATA_EH_RESET))
  			continue;
  
  		rc = ata_eh_reset(link, ata_link_nr_vacant(link),
  				  prereset, softreset, hardreset, postreset);
  		if (rc) {
  			ata_link_err(link, "reset failed, giving up\n");
  			goto out;
  		}
  	}
  
  	do {
  		unsigned long now;
  
  		/*
  		 * clears ATA_EH_PARK in eh_info and resets
  		 * ap->park_req_pending
  		 */
  		ata_eh_pull_park_action(ap);
  
  		deadline = jiffies;
  		ata_for_each_link(link, ap, EDGE) {
  			ata_for_each_dev(dev, link, ALL) {
  				struct ata_eh_context *ehc = &link->eh_context;
  				unsigned long tmp;
  
  				if (dev->class != ATA_DEV_ATA)
  					continue;
  				if (!(ehc->i.dev_action[dev->devno] &
  				      ATA_EH_PARK))
  					continue;
  				tmp = dev->unpark_deadline;
  				if (time_before(deadline, tmp))
  					deadline = tmp;
  				else if (time_before_eq(tmp, jiffies))
  					continue;
  				if (ehc->unloaded_mask & (1 << dev->devno))
  					continue;
  
  				ata_eh_park_issue_cmd(dev, 1);
  			}
  		}
  
  		now = jiffies;
  		if (time_before_eq(deadline, now))
  			break;
  
  		ata_eh_release(ap);
  		deadline = wait_for_completion_timeout(&ap->park_req_pending,
  						       deadline - now);
  		ata_eh_acquire(ap);
  	} while (deadline);
  	ata_for_each_link(link, ap, EDGE) {
  		ata_for_each_dev(dev, link, ALL) {
  			if (!(link->eh_context.unloaded_mask &
  			      (1 << dev->devno)))
  				continue;
  
  			ata_eh_park_issue_cmd(dev, 0);
  			ata_eh_done(link, dev, ATA_EH_PARK);
  		}
  	}
  
  	/* the rest */
  	nr_fails = 0;
  	ata_for_each_link(link, ap, PMP_FIRST) {
  		struct ata_eh_context *ehc = &link->eh_context;
  
  		if (sata_pmp_attached(ap) && ata_is_host_link(link))
  			goto config_lpm;
  
  		/* revalidate existing devices and attach new ones */
  		rc = ata_eh_revalidate_and_attach(link, &dev);
  		if (rc)
  			goto rest_fail;
  
  		/* if PMP got attached, return, pmp EH will take care of it */
  		if (link->device->class == ATA_DEV_PMP) {
  			ehc->i.action = 0;
  			return 0;
  		}
  
  		/* configure transfer mode if necessary */
  		if (ehc->i.flags & ATA_EHI_SETMODE) {
  			rc = ata_set_mode(link, &dev);
  			if (rc)
  				goto rest_fail;
  			ehc->i.flags &= ~ATA_EHI_SETMODE;
  		}
  
  		/* If reset has been issued, clear UA to avoid
  		 * disrupting the current users of the device.
  		 */
  		if (ehc->i.flags & ATA_EHI_DID_RESET) {
  			ata_for_each_dev(dev, link, ALL) {
  				if (dev->class != ATA_DEV_ATAPI)
  					continue;
  				rc = atapi_eh_clear_ua(dev);
  				if (rc)
  					goto rest_fail;
  			}
  		}
  
  		/* retry flush if necessary */
  		ata_for_each_dev(dev, link, ALL) {
  			if (dev->class != ATA_DEV_ATA)
  				continue;
  			rc = ata_eh_maybe_retry_flush(dev);
  			if (rc)
  				goto rest_fail;
  		}
  
  	config_lpm:
  		/* configure link power saving */
  		if (link->lpm_policy != ap->target_lpm_policy) {
  			rc = ata_eh_set_lpm(link, ap->target_lpm_policy, &dev);
  			if (rc)
  				goto rest_fail;
  		}
  
  		/* this link is okay now */
  		ehc->i.flags = 0;
  		continue;
  
  	rest_fail:
  		nr_fails++;
  		if (dev)
  			ata_eh_handle_dev_fail(dev, rc);
  
  		if (ap->pflags & ATA_PFLAG_FROZEN) {
  			/* PMP reset requires working host port.
  			 * Can't retry if it's frozen.
  			 */
  			if (sata_pmp_attached(ap))
  				goto out;
  			break;
  		}
  	}
  
  	if (nr_fails)
  		goto retry;
  
   out:
  	if (rc && r_failed_link)
  		*r_failed_link = link;
  
  	DPRINTK("EXIT, rc=%d\n", rc);
  	return rc;
  }
  
  /**
   *	ata_eh_finish - finish up EH
   *	@ap: host port to finish EH for
   *
   *	Recovery is complete.  Clean up EH states and retry or finish
   *	failed qcs.
   *
   *	LOCKING:
   *	None.
   */
  void ata_eh_finish(struct ata_port *ap)
  {
  	int tag;
  
  	/* retry or finish qcs */
  	for (tag = 0; tag < ATA_MAX_QUEUE; tag++) {
  		struct ata_queued_cmd *qc = __ata_qc_from_tag(ap, tag);
  
  		if (!(qc->flags & ATA_QCFLAG_FAILED))
  			continue;
  
  		if (qc->err_mask) {
  			/* FIXME: Once EH migration is complete,
  			 * generate sense data in this function,
  			 * considering both err_mask and tf.
  			 */
  			if (qc->flags & ATA_QCFLAG_RETRY)
  				ata_eh_qc_retry(qc);
  			else
  				ata_eh_qc_complete(qc);
  		} else {
  			if (qc->flags & ATA_QCFLAG_SENSE_VALID) {
  				ata_eh_qc_complete(qc);
  			} else {
  				/* feed zero TF to sense generation */
  				memset(&qc->result_tf, 0, sizeof(qc->result_tf));
  				ata_eh_qc_retry(qc);
  			}
  		}
  	}
  
  	/* make sure nr_active_links is zero after EH */
  	WARN_ON(ap->nr_active_links);
  	ap->nr_active_links = 0;
  }
  
  /**
   *	ata_do_eh - do standard error handling
   *	@ap: host port to handle error for
   *
   *	@prereset: prereset method (can be NULL)
   *	@softreset: softreset method (can be NULL)
   *	@hardreset: hardreset method (can be NULL)
   *	@postreset: postreset method (can be NULL)
   *
   *	Perform standard error handling sequence.
   *
   *	LOCKING:
   *	Kernel thread context (may sleep).
   */
  void ata_do_eh(struct ata_port *ap, ata_prereset_fn_t prereset,
  	       ata_reset_fn_t softreset, ata_reset_fn_t hardreset,
  	       ata_postreset_fn_t postreset)
  {
  	struct ata_device *dev;
  	int rc;
  
  	ata_eh_autopsy(ap);
  	ata_eh_report(ap);
  
  	rc = ata_eh_recover(ap, prereset, softreset, hardreset, postreset,
  			    NULL);
  	if (rc) {
  		ata_for_each_dev(dev, &ap->link, ALL)
  			ata_dev_disable(dev);
  	}
  
  	ata_eh_finish(ap);
  }
  
  /**
   *	ata_std_error_handler - standard error handler
   *	@ap: host port to handle error for
   *
   *	Standard error handler
   *
   *	LOCKING:
   *	Kernel thread context (may sleep).
   */
  void ata_std_error_handler(struct ata_port *ap)
  {
  	struct ata_port_operations *ops = ap->ops;
  	ata_reset_fn_t hardreset = ops->hardreset;
  
  	/* ignore built-in hardreset if SCR access is not available */
  	if (hardreset == sata_std_hardreset && !sata_scr_valid(&ap->link))
  		hardreset = NULL;
  
  	ata_do_eh(ap, ops->prereset, ops->softreset, hardreset, ops->postreset);
  }
  
  #ifdef CONFIG_PM
  /**
   *	ata_eh_handle_port_suspend - perform port suspend operation
   *	@ap: port to suspend
   *
   *	Suspend @ap.
   *
   *	LOCKING:
   *	Kernel thread context (may sleep).
   */
  static void ata_eh_handle_port_suspend(struct ata_port *ap)
  {
  	unsigned long flags;
  	int rc = 0;
  
  	/* are we suspending? */
  	spin_lock_irqsave(ap->lock, flags);
  	if (!(ap->pflags & ATA_PFLAG_PM_PENDING) ||
  	    ap->pm_mesg.event == PM_EVENT_ON) {
  		spin_unlock_irqrestore(ap->lock, flags);
  		return;
  	}
  	spin_unlock_irqrestore(ap->lock, flags);
  
  	WARN_ON(ap->pflags & ATA_PFLAG_SUSPENDED);
  
  	/* tell ACPI we're suspending */
  	rc = ata_acpi_on_suspend(ap);
  	if (rc)
  		goto out;
  
  	/* suspend */
  	ata_eh_freeze_port(ap);
  
  	if (ap->ops->port_suspend)
  		rc = ap->ops->port_suspend(ap, ap->pm_mesg);
  
  	ata_acpi_set_state(ap, PMSG_SUSPEND);
   out:
  	/* report result */
  	spin_lock_irqsave(ap->lock, flags);
  
  	ap->pflags &= ~ATA_PFLAG_PM_PENDING;
  	if (rc == 0)
  		ap->pflags |= ATA_PFLAG_SUSPENDED;
  	else if (ap->pflags & ATA_PFLAG_FROZEN)
  		ata_port_schedule_eh(ap);
  
  	if (ap->pm_result) {
  		*ap->pm_result = rc;
  		ap->pm_result = NULL;
  	}
  
  	spin_unlock_irqrestore(ap->lock, flags);
  
  	return;
  }
  
  /**
   *	ata_eh_handle_port_resume - perform port resume operation
   *	@ap: port to resume
   *
   *	Resume @ap.
   *
   *	LOCKING:
   *	Kernel thread context (may sleep).
   */
  static void ata_eh_handle_port_resume(struct ata_port *ap)
  {
  	struct ata_link *link;
  	struct ata_device *dev;
  	unsigned long flags;
  	int rc = 0;
  
  	/* are we resuming? */
  	spin_lock_irqsave(ap->lock, flags);
  	if (!(ap->pflags & ATA_PFLAG_PM_PENDING) ||
  	    ap->pm_mesg.event != PM_EVENT_ON) {
  		spin_unlock_irqrestore(ap->lock, flags);
  		return;
  	}
  	spin_unlock_irqrestore(ap->lock, flags);
  
  	WARN_ON(!(ap->pflags & ATA_PFLAG_SUSPENDED));
  
  	/*
  	 * Error timestamps are in jiffies which doesn't run while
  	 * suspended and PHY events during resume isn't too uncommon.
  	 * When the two are combined, it can lead to unnecessary speed
  	 * downs if the machine is suspended and resumed repeatedly.
  	 * Clear error history.
  	 */
  	ata_for_each_link(link, ap, HOST_FIRST)
  		ata_for_each_dev(dev, link, ALL)
  			ata_ering_clear(&dev->ering);
  
  	ata_acpi_set_state(ap, PMSG_ON);
  
  	if (ap->ops->port_resume)
  		rc = ap->ops->port_resume(ap);
  
  	/* tell ACPI that we're resuming */
  	ata_acpi_on_resume(ap);
  
  	/* report result */
  	spin_lock_irqsave(ap->lock, flags);
  	ap->pflags &= ~(ATA_PFLAG_PM_PENDING | ATA_PFLAG_SUSPENDED);
  	if (ap->pm_result) {
  		*ap->pm_result = rc;
  		ap->pm_result = NULL;
  	}
  	spin_unlock_irqrestore(ap->lock, flags);
  }
  #endif /* CONFIG_PM */
  