text: #ifndef _USB_VIDEO_H_
  #define _USB_VIDEO_H_
  
  #include <linux/kernel.h>
  #include <linux/videodev2.h>
  
  /*
   * Dynamic controls
   */
  
  /* Data types for UVC control data */
  #define UVC_CTRL_DATA_TYPE_RAW		0
  #define UVC_CTRL_DATA_TYPE_SIGNED	1
  #define UVC_CTRL_DATA_TYPE_UNSIGNED	2
  #define UVC_CTRL_DATA_TYPE_BOOLEAN	3
  #define UVC_CTRL_DATA_TYPE_ENUM		4
  #define UVC_CTRL_DATA_TYPE_BITMASK	5
  
  /* Control flags */
  #define UVC_CONTROL_SET_CUR	(1 << 0)
  #define UVC_CONTROL_GET_CUR	(1 << 1)
  #define UVC_CONTROL_GET_MIN	(1 << 2)
  #define UVC_CONTROL_GET_MAX	(1 << 3)
  #define UVC_CONTROL_GET_RES	(1 << 4)
  #define UVC_CONTROL_GET_DEF	(1 << 5)
  /* Control should be saved at suspend and restored at resume. */
  #define UVC_CONTROL_RESTORE	(1 << 6)
  /* Control can be updated by the camera. */
  #define UVC_CONTROL_AUTO_UPDATE	(1 << 7)
  
  #define UVC_CONTROL_GET_RANGE	(UVC_CONTROL_GET_CUR | UVC_CONTROL_GET_MIN | \
  				 UVC_CONTROL_GET_MAX | UVC_CONTROL_GET_RES | \
  				 UVC_CONTROL_GET_DEF)
  
  struct uvc_xu_control_info {
  	__u8 entity[16];
  	__u8 index;
  	__u8 selector;
  	__u16 size;
  	__u32 flags;
  };
  
  struct uvc_xu_control_mapping {
  	__u32 id;
  	__u8 name[32];
  	__u8 entity[16];
  	__u8 selector;
  
  	__u8 size;
  	__u8 offset;
  	enum v4l2_ctrl_type v4l2_type;
  	__u32 data_type;
  };
  
  struct uvc_xu_control {
  	__u8 unit;
  	__u8 selector;
  	__u16 size;
  	__u8 __user *data;
  };
  
  #define UVCIOC_CTRL_ADD		_IOW('U', 1, struct uvc_xu_control_info)
  #define UVCIOC_CTRL_MAP		_IOWR('U', 2, struct uvc_xu_control_mapping)
  #define UVCIOC_CTRL_GET		_IOWR('U', 3, struct uvc_xu_control)
  #define UVCIOC_CTRL_SET		_IOW('U', 4, struct uvc_xu_control)
  
  #ifdef __KERNEL__
  
  #include <linux/poll.h>
  #include <linux/usb/video.h>
  
  /* --------------------------------------------------------------------------
   * UVC constants
   */
  
  #define UVC_TERM_INPUT			0x0000
  #define UVC_TERM_OUTPUT			0x8000
  #define UVC_TERM_DIRECTION(term)	((term)->type & 0x8000)
  
  #define UVC_ENTITY_TYPE(entity)		((entity)->type & 0x7fff)
  #define UVC_ENTITY_IS_UNIT(entity)	(((entity)->type & 0xff00) == 0)
  #define UVC_ENTITY_IS_TERM(entity)	(((entity)->type & 0xff00) != 0)
  #define UVC_ENTITY_IS_ITERM(entity) \
  	(UVC_ENTITY_IS_TERM(entity) && \
  	((entity)->type & 0x8000) == UVC_TERM_INPUT)
  #define UVC_ENTITY_IS_OTERM(entity) \
  	(UVC_ENTITY_IS_TERM(entity) && \
  	((entity)->type & 0x8000) == UVC_TERM_OUTPUT)
  
  
  /* ------------------------------------------------------------------------
   * GUIDs
   */
  #define UVC_GUID_UVC_CAMERA \
  	{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, \
  	 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01}
  #define UVC_GUID_UVC_OUTPUT \
  	{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, \
  	 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02}
  #define UVC_GUID_UVC_MEDIA_TRANSPORT_INPUT \
  	{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, \
  	 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x03}
  #define UVC_GUID_UVC_PROCESSING \
  	{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, \
  	 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x01}
  #define UVC_GUID_UVC_SELECTOR \
  	{0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, \
  	 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x02}
  
  #define UVC_GUID_FORMAT_MJPEG \
  	{ 'M',  'J',  'P',  'G', 0x00, 0x00, 0x10, 0x00, \
  	 0x80, 0x00, 0x00, 0xaa, 0x00, 0x38, 0x9b, 0x71}
  #define UVC_GUID_FORMAT_YUY2 \
  	{ 'Y',  'U',  'Y',  '2', 0x00, 0x00, 0x10, 0x00, \
  	 0x80, 0x00, 0x00, 0xaa, 0x00, 0x38, 0x9b, 0x71}
  #define UVC_GUID_FORMAT_YUY2_ISIGHT \
  	{ 'Y',  'U',  'Y',  '2', 0x00, 0x00, 0x10, 0x00, \
  	 0x80, 0x00, 0x00, 0x00, 0x00, 0x38, 0x9b, 0x71}
  #define UVC_GUID_FORMAT_NV12 \
  	{ 'N',  'V',  '1',  '2', 0x00, 0x00, 0x10, 0x00, \
  	 0x80, 0x00, 0x00, 0xaa, 0x00, 0x38, 0x9b, 0x71}
  #define UVC_GUID_FORMAT_YV12 \
  	{ 'Y',  'V',  '1',  '2', 0x00, 0x00, 0x10, 0x00, \
  	 0x80, 0x00, 0x00, 0xaa, 0x00, 0x38, 0x9b, 0x71}
  #define UVC_GUID_FORMAT_I420 \
  	{ 'I',  '4',  '2',  '0', 0x00, 0x00, 0x10, 0x00, \
  	 0x80, 0x00, 0x00, 0xaa, 0x00, 0x38, 0x9b, 0x71}
  #define UVC_GUID_FORMAT_UYVY \
  	{ 'U',  'Y',  'V',  'Y', 0x00, 0x00, 0x10, 0x00, \
  	 0x80, 0x00, 0x00, 0xaa, 0x00, 0x38, 0x9b, 0x71}
  #define UVC_GUID_FORMAT_Y800 \
  	{ 'Y',  '8',  '0',  '0', 0x00, 0x00, 0x10, 0x00, \
  	 0x80, 0x00, 0x00, 0xaa, 0x00, 0x38, 0x9b, 0x71}
  #define UVC_GUID_FORMAT_Y16 \
  	{ 'Y',  '1',  '6',  ' ', 0x00, 0x00, 0x10, 0x00, \
  	 0x80, 0x00, 0x00, 0xaa, 0x00, 0x38, 0x9b, 0x71}
  #define UVC_GUID_FORMAT_BY8 \
  	{ 'B',  'Y',  '8',  ' ', 0x00, 0x00, 0x10, 0x00, \
  	 0x80, 0x00, 0x00, 0xaa, 0x00, 0x38, 0x9b, 0x71}
  
  /* ------------------------------------------------------------------------
   * Driver specific constants.
   */
  
  #define DRIVER_VERSION_NUMBER	KERNEL_VERSION(0, 1, 0)
  
  /* Number of isochronous URBs. */
  #define UVC_URBS		5
  /* Maximum number of packets per URB. */
  #define UVC_MAX_PACKETS		32
  /* Maximum number of video buffers. */
  #define UVC_MAX_VIDEO_BUFFERS	32
  /* Maximum status buffer size in bytes of interrupt URB. */
  #define UVC_MAX_STATUS_SIZE	16
  
  #define UVC_CTRL_CONTROL_TIMEOUT	300
  #define UVC_CTRL_STREAMING_TIMEOUT	5000
  
  /* Devices quirks */
  #define UVC_QUIRK_STATUS_INTERVAL	0x00000001
  #define UVC_QUIRK_PROBE_MINMAX		0x00000002
  #define UVC_QUIRK_PROBE_EXTRAFIELDS	0x00000004
  #define UVC_QUIRK_BUILTIN_ISIGHT	0x00000008
  #define UVC_QUIRK_STREAM_NO_FID		0x00000010
  #define UVC_QUIRK_IGNORE_SELECTOR_UNIT	0x00000020
  #define UVC_QUIRK_FIX_BANDWIDTH		0x00000080
  #define UVC_QUIRK_PROBE_DEF		0x00000100
  
  /* Format flags */
  #define UVC_FMT_FLAG_COMPRESSED		0x00000001
  #define UVC_FMT_FLAG_STREAM		0x00000002
  
  /* ------------------------------------------------------------------------
   * Structures.
   */
  
  struct uvc_device;
  
  /* TODO: Put the most frequently accessed fields at the beginning of
   * structures to maximize cache efficiency.
   */
  struct uvc_streaming_control {
  	__u16 bmHint;
  	__u8  bFormatIndex;
  	__u8  bFrameIndex;
  	__u32 dwFrameInterval;
  	__u16 wKeyFrameRate;
  	__u16 wPFrameRate;
  	__u16 wCompQuality;
  	__u16 wCompWindowSize;
  	__u16 wDelay;
  	__u32 dwMaxVideoFrameSize;
  	__u32 dwMaxPayloadTransferSize;
  	__u32 dwClockFrequency;
  	__u8  bmFramingInfo;
  	__u8  bPreferedVersion;
  	__u8  bMinVersion;
  	__u8  bMaxVersion;
  };
  
  struct uvc_menu_info {
  	__u32 value;
  	__u8 name[32];
  };
  
  struct uvc_control_info {
  	struct list_head list;
  	struct list_head mappings;
  
  	__u8 entity[16];
  	__u8 index;
  	__u8 selector;
  
  	__u16 size;
  	__u32 flags;
  };
  
  struct uvc_control_mapping {
  	struct list_head list;
  
  	struct uvc_control_info *ctrl;
  
  	__u32 id;
  	__u8 name[32];
  	__u8 entity[16];
  	__u8 selector;
  
  	__u8 size;
  	__u8 offset;
  	enum v4l2_ctrl_type v4l2_type;
  	__u32 data_type;
  
  	struct uvc_menu_info *menu_info;
  	__u32 menu_count;
  
  	__s32 (*get) (struct uvc_control_mapping *mapping, __u8 query,
  		      const __u8 *data);
  	void (*set) (struct uvc_control_mapping *mapping, __s32 value,
  		     __u8 *data);
  };
  
  struct uvc_control {
  	struct uvc_entity *entity;
  	struct uvc_control_info *info;
  
  	__u8 index;	/* Used to match the uvc_control entry with a
  			   uvc_control_info. */
  	__u8 dirty : 1,
  	     loaded : 1,
  	     modified : 1,
  	     cached : 1;
  
  	__u8 *data;
  };
  
  struct uvc_format_desc {
  	char *name;
  	__u8 guid[16];
  	__u32 fcc;
  };
  
  /* The term 'entity' refers to both UVC units and UVC terminals.
   *
   * The type field is either the terminal type (wTerminalType in the terminal
   * descriptor), or the unit type (bDescriptorSubtype in the unit descriptor).
   * As the bDescriptorSubtype field is one byte long, the type value will
   * always have a null MSB for units. All terminal types defined by the UVC
   * specification have a non-null MSB, so it is safe to use the MSB to
   * differentiate between units and terminals as long as the descriptor parsing
   * code makes sure terminal types have a non-null MSB.
   *
   * For terminals, the type's most significant bit stores the terminal
   * direction (either UVC_TERM_INPUT or UVC_TERM_OUTPUT). The type field should
   * always be accessed with the UVC_ENTITY_* macros and never directly.
   */
  
  struct uvc_entity {
  	struct list_head list;		/* Entity as part of a UVC device. */
  	struct list_head chain;		/* Entity as part of a video device
  					 * chain. */
  	__u8 id;
  	__u16 type;
  	char name[64];
  
  	union {
  		struct {
  			__u16 wObjectiveFocalLengthMin;
  			__u16 wObjectiveFocalLengthMax;
  			__u16 wOcularFocalLength;
  			__u8  bControlSize;
  			__u8  *bmControls;
  		} camera;
  
  		struct {
  			__u8  bControlSize;
  			__u8  *bmControls;
  			__u8  bTransportModeSize;
  			__u8  *bmTransportModes;
  		} media;
  
  		struct {
  		} output;
  
  		struct {
  			__u16 wMaxMultiplier;
  			__u8  bControlSize;
  			__u8  *bmControls;
  			__u8  bmVideoStandards;
  		} processing;
  
  		struct {
  		} selector;
  
  		struct {
  			__u8  guidExtensionCode[16];
  			__u8  bNumControls;
  			__u8  bControlSize;
  			__u8  *bmControls;
  			__u8  *bmControlsType;
  		} extension;
  	};
  
  	__u8 bNrInPins;
  	__u8 *baSourceID;
  
  	unsigned int ncontrols;
  	struct uvc_control *controls;
  };
  
  struct uvc_frame {
  	__u8  bFrameIndex;
  	__u8  bmCapabilities;
  	__u16 wWidth;
  	__u16 wHeight;
  	__u32 dwMinBitRate;
  	__u32 dwMaxBitRate;
  	__u32 dwMaxVideoFrameBufferSize;
  	__u8  bFrameIntervalType;
  	__u32 dwDefaultFrameInterval;
  	__u32 *dwFrameInterval;
  };
  
  struct uvc_format {
  	__u8 type;
  	__u8 index;
  	__u8 bpp;
  	__u8 colorspace;
  	__u32 fcc;
  	__u32 flags;
  
  	char name[32];
  
  	unsigned int nframes;
  	struct uvc_frame *frame;
  };
  
  struct uvc_streaming_header {
  	__u8 bNumFormats;
  	__u8 bEndpointAddress;
  	__u8 bTerminalLink;
  	__u8 bControlSize;
  	__u8 *bmaControls;
  	/* The following fields are used by input headers only. */
  	__u8 bmInfo;
  	__u8 bStillCaptureMethod;
  	__u8 bTriggerSupport;
  	__u8 bTriggerUsage;
  };
  
  enum uvc_buffer_state {
  	UVC_BUF_STATE_IDLE	= 0,
  	UVC_BUF_STATE_QUEUED	= 1,
  	UVC_BUF_STATE_ACTIVE	= 2,
  	UVC_BUF_STATE_READY	= 3,
  	UVC_BUF_STATE_DONE	= 4,
  	UVC_BUF_STATE_ERROR	= 5,
  };
  
  struct uvc_buffer {
  	unsigned long vma_use_count;
  	struct list_head stream;
  
  	/* Touched by interrupt handler. */
  	struct v4l2_buffer buf;
  	struct list_head queue;
  	wait_queue_head_t wait;
  	enum uvc_buffer_state state;
  };
  
  #define UVC_QUEUE_STREAMING		(1 << 0)
  #define UVC_QUEUE_DISCONNECTED		(1 << 1)
  #define UVC_QUEUE_DROP_INCOMPLETE	(1 << 2)
  
  struct uvc_video_queue {
  	enum v4l2_buf_type type;
  
  	void *mem;
  	unsigned int flags;
  	__u32 sequence;
  
  	unsigned int count;
  	unsigned int buf_size;
  	unsigned int buf_used;
  	struct uvc_buffer buffer[UVC_MAX_VIDEO_BUFFERS];
  	struct mutex mutex;	/* protects buffers and mainqueue */
  	spinlock_t irqlock;	/* protects irqqueue */
  
  	struct list_head mainqueue;
  	struct list_head irqqueue;
  };
  
  struct uvc_video_chain {
  	struct uvc_device *dev;
  	struct list_head list;
  
  	struct list_head entities;		/* All entities */
  	struct uvc_entity *processing;		/* Processing unit */
  	struct uvc_entity *selector;		/* Selector unit */
  
  	struct mutex ctrl_mutex;
  };
  
  struct uvc_streaming {
  	struct list_head list;
  	struct uvc_device *dev;
  	struct video_device *vdev;
  	struct uvc_video_chain *chain;
  	atomic_t active;
  
  	struct usb_interface *intf;
  	int intfnum;
  	__u16 maxpsize;
  
  	struct uvc_streaming_header header;
  	enum v4l2_buf_type type;
  
  	unsigned int nformats;
  	struct uvc_format *format;
  
  	struct uvc_streaming_control ctrl;
  	struct uvc_format *cur_format;
  	struct uvc_frame *cur_frame;
  
  	struct mutex mutex;
  
  	unsigned int frozen : 1;
  	struct uvc_video_queue queue;
  	void (*decode) (struct urb *urb, struct uvc_streaming *video,
  			struct uvc_buffer *buf);
  
  	/* Context data used by the bulk completion handler. */
  	struct {
  		__u8 header[256];
  		unsigned int header_size;
  		int skip_payload;
  		__u32 payload_size;
  		__u32 max_payload_size;
  	} bulk;
  
  	struct urb *urb[UVC_URBS];
  	char *urb_buffer[UVC_URBS];
  	dma_addr_t urb_dma[UVC_URBS];
  	unsigned int urb_size;
  
  	__u8 last_fid;
  };
  
  enum uvc_device_state {
  	UVC_DEV_DISCONNECTED = 1,
  };
  
  struct uvc_device {
  	struct usb_device *udev;
  	struct usb_interface *intf;
  	unsigned long warnings;
  	__u32 quirks;
  	int intfnum;
  	char name[32];
  
  	enum uvc_device_state state;
  	struct list_head list;
  	atomic_t users;
  
  	/* Video control interface */
  	__u16 uvc_version;
  	__u32 clock_frequency;
  
  	struct list_head entities;
  	struct list_head chains;
  
  	/* Video Streaming interfaces */
  	struct list_head streams;
  	atomic_t nstreams;
  
  	/* Status Interrupt Endpoint */
  	struct usb_host_endpoint *int_ep;
  	struct urb *int_urb;
  	__u8 *status;
  	struct input_dev *input;
  	char input_phys[64];
  };
  
  enum uvc_handle_state {
  	UVC_HANDLE_PASSIVE	= 0,
  	UVC_HANDLE_ACTIVE	= 1,
  };
  
  struct uvc_fh {
  	struct uvc_video_chain *chain;
  	struct uvc_streaming *stream;
  	enum uvc_handle_state state;
  };
  
  struct uvc_driver {
  	struct usb_driver driver;
  
  	struct list_head devices;	/* struct uvc_device list */
  	struct list_head controls;	/* struct uvc_control_info list */
  	struct mutex ctrl_mutex;	/* protects controls and devices
  					   lists */
  };
  
  /* ------------------------------------------------------------------------
   * Debugging, printing and logging
   */
  
  #define UVC_TRACE_PROBE		(1 << 0)
  #define UVC_TRACE_DESCR		(1 << 1)
  #define UVC_TRACE_CONTROL	(1 << 2)
  #define UVC_TRACE_FORMAT	(1 << 3)
  #define UVC_TRACE_CAPTURE	(1 << 4)
  #define UVC_TRACE_CALLS		(1 << 5)
  #define UVC_TRACE_IOCTL		(1 << 6)
  #define UVC_TRACE_FRAME		(1 << 7)
  #define UVC_TRACE_SUSPEND	(1 << 8)
  #define UVC_TRACE_STATUS	(1 << 9)
  #define UVC_TRACE_VIDEO		(1 << 10)
  
  #define UVC_WARN_MINMAX		0
  #define UVC_WARN_PROBE_DEF	1
  
  extern unsigned int uvc_clock_param;
  extern unsigned int uvc_no_drop_param;
  extern unsigned int uvc_trace_param;
  extern unsigned int uvc_timeout_param;
  
  #define uvc_trace(flag, msg...) \
  	do { \
  		if (uvc_trace_param & flag) \
  			printk(KERN_DEBUG "uvcvideo: " msg); \
  	} while (0)
  
  #define uvc_warn_once(dev, warn, msg...) \
  	do { \
  		if (!test_and_set_bit(warn, &dev->warnings)) \
  			printk(KERN_INFO "uvcvideo: " msg); \
  	} while (0)
  
  #define uvc_printk(level, msg...) \
  	printk(level "uvcvideo: " msg)
  
  /* --------------------------------------------------------------------------
   * Internal functions.
   */
  
  /* Core driver */
  extern struct uvc_driver uvc_driver;
  
  /* Video buffers queue management. */
  extern void uvc_queue_init(struct uvc_video_queue *queue,
  		enum v4l2_buf_type type);
  extern int uvc_alloc_buffers(struct uvc_video_queue *queue,
  		unsigned int nbuffers, unsigned int buflength);
  extern int uvc_free_buffers(struct uvc_video_queue *queue);
  extern int uvc_query_buffer(struct uvc_video_queue *queue,
  		struct v4l2_buffer *v4l2_buf);
  extern int uvc_queue_buffer(struct uvc_video_queue *queue,
  		struct v4l2_buffer *v4l2_buf);
  extern int uvc_dequeue_buffer(struct uvc_video_queue *queue,
  		struct v4l2_buffer *v4l2_buf, int nonblocking);
  extern int uvc_queue_enable(struct uvc_video_queue *queue, int enable);
  extern void uvc_queue_cancel(struct uvc_video_queue *queue, int disconnect);
  extern struct uvc_buffer *uvc_queue_next_buffer(struct uvc_video_queue *queue,
  		struct uvc_buffer *buf);
  extern unsigned int uvc_queue_poll(struct uvc_video_queue *queue,
  		struct file *file, poll_table *wait);
  extern int uvc_queue_allocated(struct uvc_video_queue *queue);
  static inline int uvc_queue_streaming(struct uvc_video_queue *queue)
  {
  	return queue->flags & UVC_QUEUE_STREAMING;
  }
  
  /* V4L2 interface */
  extern const struct v4l2_file_operations uvc_fops;
  
  /* Video */
  extern int uvc_video_init(struct uvc_streaming *stream);
  extern int uvc_video_suspend(struct uvc_streaming *stream);
  extern int uvc_video_resume(struct uvc_streaming *stream);
  extern int uvc_video_enable(struct uvc_streaming *stream, int enable);
  extern int uvc_probe_video(struct uvc_streaming *stream,
  		struct uvc_streaming_control *probe);
  extern int uvc_commit_video(struct uvc_streaming *stream,
  		struct uvc_streaming_control *ctrl);
  extern int uvc_query_ctrl(struct uvc_device *dev, __u8 query, __u8 unit,
  		__u8 intfnum, __u8 cs, void *data, __u16 size);
  
  /* Status */
  extern int uvc_status_init(struct uvc_device *dev);
  extern void uvc_status_cleanup(struct uvc_device *dev);
  extern int uvc_status_start(struct uvc_device *dev);
  extern void uvc_status_stop(struct uvc_device *dev);
  extern int uvc_status_suspend(struct uvc_device *dev);
  extern int uvc_status_resume(struct uvc_device *dev);
  
  /* Controls */
  extern struct uvc_control *uvc_find_control(struct uvc_video_chain *chain,
  		__u32 v4l2_id, struct uvc_control_mapping **mapping);
  extern int uvc_query_v4l2_ctrl(struct uvc_video_chain *chain,
  		struct v4l2_queryctrl *v4l2_ctrl);
  
  extern int uvc_ctrl_add_info(struct uvc_control_info *info);
  extern int uvc_ctrl_add_mapping(struct uvc_control_mapping *mapping);
  extern int uvc_ctrl_init_device(struct uvc_device *dev);
  extern void uvc_ctrl_cleanup_device(struct uvc_device *dev);
  extern int uvc_ctrl_resume_device(struct uvc_device *dev);
  extern void uvc_ctrl_init(void);
  
  extern int uvc_ctrl_begin(struct uvc_video_chain *chain);
  extern int __uvc_ctrl_commit(struct uvc_video_chain *chain, int rollback);
  static inline int uvc_ctrl_commit(struct uvc_video_chain *chain)
  {
  	return __uvc_ctrl_commit(chain, 0);
  }
  static inline int uvc_ctrl_rollback(struct uvc_video_chain *chain)
  {
  	return __uvc_ctrl_commit(chain, 1);
  }
  
  extern int uvc_ctrl_get(struct uvc_video_chain *chain,
  		struct v4l2_ext_control *xctrl);
  extern int uvc_ctrl_set(struct uvc_video_chain *chain,
  		struct v4l2_ext_control *xctrl);
  
  extern int uvc_xu_ctrl_query(struct uvc_video_chain *chain,
  		struct uvc_xu_control *ctrl, int set);
  
  /* Utility functions */
  extern void uvc_simplify_fraction(uint32_t *numerator, uint32_t *denominator,
  		unsigned int n_terms, unsigned int threshold);
  extern uint32_t uvc_fraction_to_interval(uint32_t numerator,
  		uint32_t denominator);
  extern struct usb_host_endpoint *uvc_find_endpoint(
  		struct usb_host_interface *alts, __u8 epaddr);
  
  /* Quirks support */
  void uvc_video_decode_isight(struct urb *urb, struct uvc_streaming *stream,
  		struct uvc_buffer *buf);
  
  #endif /* __KERNEL__ */
  
  #endif
  
  