text: /*
   * Copyright (C) 2014 Red Hat
   * Copyright (C) 2014 Intel Corp.
   *
   * Permission is hereby granted, free of charge, to any person obtaining a
   * copy of this software and associated documentation files (the "Software"),
   * to deal in the Software without restriction, including without limitation
   * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   * and/or sell copies of the Software, and to permit persons to whom the
   * Software is furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice shall be included in
   * all copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
   * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
   * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
   * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
   * OTHER DEALINGS IN THE SOFTWARE.
   *
   * Authors:
   * Rob Clark <robdclark@gmail.com>
   * Daniel Vetter <daniel.vetter@ffwll.ch>
   */
  
  #include <drm/drmP.h>
  #include <drm/drm_atomic.h>
  #include <drm/drm_plane_helper.h>
  #include <drm/drm_crtc_helper.h>
  #include <drm/drm_atomic_helper.h>
  #include <linux/fence.h>
  
  /**
   * DOC: overview
   *
   * This helper library provides implementations of check and commit functions on
   * top of the CRTC modeset helper callbacks and the plane helper callbacks. It
   * also provides convenience implementations for the atomic state handling
   * callbacks for drivers which don't need to subclass the drm core structures to
   * add their own additional internal state.
   *
   * This library also provides default implementations for the check callback in
   * drm_atomic_helper_check and for the commit callback with
   * drm_atomic_helper_commit. But the individual stages and callbacks are expose
   * to allow drivers to mix and match and e.g. use the plane helpers only
   * together with a driver private modeset implementation.
   *
   * This library also provides implementations for all the legacy driver
   * interfaces on top of the atomic interface. See drm_atomic_helper_set_config,
   * drm_atomic_helper_disable_plane, drm_atomic_helper_disable_plane and the
   * various functions to implement set_property callbacks. New drivers must not
   * implement these functions themselves but must use the provided helpers.
   */
  static void
  drm_atomic_helper_plane_changed(struct drm_atomic_state *state,
  				struct drm_plane_state *plane_state,
  				struct drm_plane *plane)
  {
  	struct drm_crtc_state *crtc_state;
  
  	if (plane->state->crtc) {
  		crtc_state = state->crtc_states[drm_crtc_index(plane->state->crtc)];
  
  		if (WARN_ON(!crtc_state))
  			return;
  
  		crtc_state->planes_changed = true;
  	}
  
  	if (plane_state->crtc) {
  		crtc_state =
  			state->crtc_states[drm_crtc_index(plane_state->crtc)];
  
  		if (WARN_ON(!crtc_state))
  			return;
  
  		crtc_state->planes_changed = true;
  	}
  }
  
  static struct drm_crtc *
  get_current_crtc_for_encoder(struct drm_device *dev,
  			     struct drm_encoder *encoder)
  {
  	struct drm_mode_config *config = &dev->mode_config;
  	struct drm_connector *connector;
  
  	WARN_ON(!drm_modeset_is_locked(&config->connection_mutex));
  
  	list_for_each_entry(connector, &config->connector_list, head) {
  		if (connector->state->best_encoder != encoder)
  			continue;
  
  		return connector->state->crtc;
  	}
  
  	return NULL;
  }
  
  static int
  steal_encoder(struct drm_atomic_state *state,
  	      struct drm_encoder *encoder,
  	      struct drm_crtc *encoder_crtc)
  {
  	struct drm_mode_config *config = &state->dev->mode_config;
  	struct drm_crtc_state *crtc_state;
  	struct drm_connector *connector;
  	struct drm_connector_state *connector_state;
  	int ret;
  
  	/*
  	 * We can only steal an encoder coming from a connector, which means we
  	 * must already hold the connection_mutex.
  	 */
  	WARN_ON(!drm_modeset_is_locked(&config->connection_mutex));
  
  	DRM_DEBUG_ATOMIC("[ENCODER:%d:%s] in use on [CRTC:%d], stealing it\n",
  			 encoder->base.id, encoder->name,
  			 encoder_crtc->base.id);
  
  	crtc_state = drm_atomic_get_crtc_state(state, encoder_crtc);
  	if (IS_ERR(crtc_state))
  		return PTR_ERR(crtc_state);
  
  	crtc_state->mode_changed = true;
  
  	list_for_each_entry(connector, &config->connector_list, head) {
  		if (connector->state->best_encoder != encoder)
  			continue;
  
  		DRM_DEBUG_ATOMIC("Stealing encoder from [CONNECTOR:%d:%s]\n",
  				 connector->base.id,
  				 connector->name);
  
  		connector_state = drm_atomic_get_connector_state(state,
  								 connector);
  		if (IS_ERR(connector_state))
  			return PTR_ERR(connector_state);
  
  		ret = drm_atomic_set_crtc_for_connector(connector_state, NULL);
  		if (ret)
  			return ret;
  		connector_state->best_encoder = NULL;
  	}
  
  	return 0;
  }
  
  static int
  update_connector_routing(struct drm_atomic_state *state, int conn_idx)
  {
  	const struct drm_connector_helper_funcs *funcs;
  	struct drm_encoder *new_encoder;
  	struct drm_crtc *encoder_crtc;
  	struct drm_connector *connector;
  	struct drm_connector_state *connector_state;
  	struct drm_crtc_state *crtc_state;
  	int idx, ret;
  
  	connector = state->connectors[conn_idx];
  	connector_state = state->connector_states[conn_idx];
  
  	if (!connector)
  		return 0;
  
  	DRM_DEBUG_ATOMIC("Updating routing for [CONNECTOR:%d:%s]\n",
  			 connector->base.id,
  			 connector->name);
  
  	if (connector->state->crtc != connector_state->crtc) {
  		if (connector->state->crtc) {
  			idx = drm_crtc_index(connector->state->crtc);
  
  			crtc_state = state->crtc_states[idx];
  			crtc_state->mode_changed = true;
  		}
  
  		if (connector_state->crtc) {
  			idx = drm_crtc_index(connector_state->crtc);
  
  			crtc_state = state->crtc_states[idx];
  			crtc_state->mode_changed = true;
  		}
  	}
  
  	if (!connector_state->crtc) {
  		DRM_DEBUG_ATOMIC("Disabling [CONNECTOR:%d:%s]\n",
  				connector->base.id,
  				connector->name);
  
  		connector_state->best_encoder = NULL;
  
  		return 0;
  	}
  
  	funcs = connector->helper_private;
  	new_encoder = funcs->best_encoder(connector);
  
  	if (!new_encoder) {
  		DRM_DEBUG_ATOMIC("No suitable encoder found for [CONNECTOR:%d:%s]\n",
  				 connector->base.id,
  				 connector->name);
  		return -EINVAL;
  	}
  
  	if (new_encoder == connector_state->best_encoder) {
  		DRM_DEBUG_ATOMIC("[CONNECTOR:%d:%s] keeps [ENCODER:%d:%s], now on [CRTC:%d]\n",
  				 connector->base.id,
  				 connector->name,
  				 new_encoder->base.id,
  				 new_encoder->name,
  				 connector_state->crtc->base.id);
  
  		return 0;
  	}
  
  	encoder_crtc = get_current_crtc_for_encoder(state->dev,
  						    new_encoder);
  
  	if (encoder_crtc) {
  		ret = steal_encoder(state, new_encoder, encoder_crtc);
  		if (ret) {
  			DRM_DEBUG_ATOMIC("Encoder stealing failed for [CONNECTOR:%d:%s]\n",
  					 connector->base.id,
  					 connector->name);
  			return ret;
  		}
  	}
  
  	connector_state->best_encoder = new_encoder;
  	idx = drm_crtc_index(connector_state->crtc);
  
  	crtc_state = state->crtc_states[idx];
  	crtc_state->mode_changed = true;
  
  	DRM_DEBUG_ATOMIC("[CONNECTOR:%d:%s] using [ENCODER:%d:%s] on [CRTC:%d]\n",
  			 connector->base.id,
  			 connector->name,
  			 new_encoder->base.id,
  			 new_encoder->name,
  			 connector_state->crtc->base.id);
  
  	return 0;
  }
  
  static int
  mode_fixup(struct drm_atomic_state *state)
  {
  	struct drm_crtc *crtc;
  	struct drm_crtc_state *crtc_state;
  	struct drm_connector *connector;
  	struct drm_connector_state *conn_state;
  	int i;
  	bool ret;
  
  	for_each_crtc_in_state(state, crtc, crtc_state, i) {
  		if (!crtc_state->mode_changed)
  			continue;
  
  		drm_mode_copy(&crtc_state->adjusted_mode, &crtc_state->mode);
  	}
  
  	for_each_connector_in_state(state, connector, conn_state, i) {
  		const struct drm_encoder_helper_funcs *funcs;
  		struct drm_encoder *encoder;
  
  		WARN_ON(!!conn_state->best_encoder != !!conn_state->crtc);
  
  		if (!conn_state->crtc || !conn_state->best_encoder)
  			continue;
  
  		crtc_state =
  			state->crtc_states[drm_crtc_index(conn_state->crtc)];
  
  		/*
  		 * Each encoder has at most one connector (since we always steal
  		 * it away), so we won't call ->mode_fixup twice.
  		 */
  		encoder = conn_state->best_encoder;
  		funcs = encoder->helper_private;
  
  		if (encoder->bridge && encoder->bridge->funcs->mode_fixup) {
  			ret = encoder->bridge->funcs->mode_fixup(
  					encoder->bridge, &crtc_state->mode,
  					&crtc_state->adjusted_mode);
  			if (!ret) {
  				DRM_DEBUG_ATOMIC("Bridge fixup failed\n");
  				return -EINVAL;
  			}
  		}
  
  		if (funcs->atomic_check) {
  			ret = funcs->atomic_check(encoder, crtc_state,
  						  conn_state);
  			if (ret) {
  				DRM_DEBUG_ATOMIC("[ENCODER:%d:%s] check failed\n",
  						 encoder->base.id, encoder->name);
  				return ret;
  			}
  		} else {
  			ret = funcs->mode_fixup(encoder, &crtc_state->mode,
  						&crtc_state->adjusted_mode);
  			if (!ret) {
  				DRM_DEBUG_ATOMIC("[ENCODER:%d:%s] fixup failed\n",
  						 encoder->base.id, encoder->name);
  				return -EINVAL;
  			}
  		}
  	}
  
  	for_each_crtc_in_state(state, crtc, crtc_state, i) {
  		const struct drm_crtc_helper_funcs *funcs;
  
  		if (!crtc_state->mode_changed)
  			continue;
  
  		funcs = crtc->helper_private;
  		ret = funcs->mode_fixup(crtc, &crtc_state->mode,
  					&crtc_state->adjusted_mode);
  		if (!ret) {
  			DRM_DEBUG_ATOMIC("[CRTC:%d] fixup failed\n",
  					 crtc->base.id);
  			return -EINVAL;
  		}
  	}
  
  	return 0;
  }
  
  static bool
  needs_modeset(struct drm_crtc_state *state)
  {
  	return state->mode_changed || state->active_changed;
  }
  
  /**
   * drm_atomic_helper_check - validate state object for modeset changes
   * @dev: DRM device
   * @state: the driver state object
   *
   * Check the state object to see if the requested state is physically possible.
   * This does all the crtc and connector related computations for an atomic
   * update. It computes and updates crtc_state->mode_changed, adds any additional
   * connectors needed for full modesets and calls down into ->mode_fixup
   * functions of the driver backend.
   *
   * IMPORTANT:
   *
   * Drivers which update ->mode_changed (e.g. in their ->atomic_check hooks if a
   * plane update can't be done without a full modeset) _must_ call this function
   * afterwards after that change. It is permitted to call this function multiple
   * times for the same update, e.g. when the ->atomic_check functions depend upon
   * the adjusted dotclock for fifo space allocation and watermark computation.
   *
   * RETURNS
   * Zero for success or -errno
   */
  int
  drm_atomic_helper_check_modeset(struct drm_device *dev,
  				struct drm_atomic_state *state)
  {
  	struct drm_crtc *crtc;
  	struct drm_crtc_state *crtc_state;
  	struct drm_connector *connector;
  	struct drm_connector_state *connector_state;
  	int i, ret;
  
  	for_each_crtc_in_state(state, crtc, crtc_state, i) {
  		if (!drm_mode_equal(&crtc->state->mode, &crtc_state->mode)) {
  			DRM_DEBUG_ATOMIC("[CRTC:%d] mode changed\n",
  					 crtc->base.id);
  			crtc_state->mode_changed = true;
  		}
  
  		if (crtc->state->enable != crtc_state->enable) {
  			DRM_DEBUG_ATOMIC("[CRTC:%d] enable changed\n",
  					 crtc->base.id);
  			crtc_state->mode_changed = true;
  		}
  	}
  
  	for_each_connector_in_state(state, connector, connector_state, i) {
  		/*
  		 * This only sets crtc->mode_changed for routing changes,
  		 * drivers must set crtc->mode_changed themselves when connector
  		 * properties need to be updated.
  		 */
  		ret = update_connector_routing(state, i);
  		if (ret)
  			return ret;
  	}
  
  	/*
  	 * After all the routing has been prepared we need to add in any
  	 * connector which is itself unchanged, but who's crtc changes it's
  	 * configuration. This must be done before calling mode_fixup in case a
  	 * crtc only changed its mode but has the same set of connectors.
  	 */
  	for_each_crtc_in_state(state, crtc, crtc_state, i) {
  		int num_connectors;
  
  		/*
  		 * We must set ->active_changed after walking connectors for
  		 * otherwise an update that only changes active would result in
  		 * a full modeset because update_connector_routing force that.
  		 */
  		if (crtc->state->active != crtc_state->active) {
  			DRM_DEBUG_ATOMIC("[CRTC:%d] active changed\n",
  					 crtc->base.id);
  			crtc_state->active_changed = true;
  		}
  
  		if (!needs_modeset(crtc_state))
  			continue;
  
  		DRM_DEBUG_ATOMIC("[CRTC:%d] needs all connectors, enable: %c, active: %c\n",
  				 crtc->base.id,
  				 crtc_state->enable ? 'y' : 'n',
  			      crtc_state->active ? 'y' : 'n');
  
  		ret = drm_atomic_add_affected_connectors(state, crtc);
  		if (ret != 0)
  			return ret;
  
  		num_connectors = drm_atomic_connectors_for_crtc(state,
  								crtc);
  
  		if (crtc_state->enable != !!num_connectors) {
  			DRM_DEBUG_ATOMIC("[CRTC:%d] enabled/connectors mismatch\n",
  					 crtc->base.id);
  
  			return -EINVAL;
  		}
  	}
  
  	return mode_fixup(state);
  }
  EXPORT_SYMBOL(drm_atomic_helper_check_modeset);
  
  /**
   * drm_atomic_helper_check - validate state object for modeset changes
   * @dev: DRM device
   * @state: the driver state object
   *
   * Check the state object to see if the requested state is physically possible.
   * This does all the plane update related checks using by calling into the
   * ->atomic_check hooks provided by the driver.
   *
   * RETURNS
   * Zero for success or -errno
   */
  int
  drm_atomic_helper_check_planes(struct drm_device *dev,
  			       struct drm_atomic_state *state)
  {
  	struct drm_crtc *crtc;
  	struct drm_crtc_state *crtc_state;
  	struct drm_plane *plane;
  	struct drm_plane_state *plane_state;
  	int i, ret = 0;
  
  	for_each_plane_in_state(state, plane, plane_state, i) {
  		const struct drm_plane_helper_funcs *funcs;
  
  		funcs = plane->helper_private;
  
  		drm_atomic_helper_plane_changed(state, plane_state, plane);
  
  		if (!funcs || !funcs->atomic_check)
  			continue;
  
  		ret = funcs->atomic_check(plane, plane_state);
  		if (ret) {
  			DRM_DEBUG_ATOMIC("[PLANE:%d] atomic driver check failed\n",
  					 plane->base.id);
  			return ret;
  		}
  	}
  
  	for_each_crtc_in_state(state, crtc, crtc_state, i) {
  		const struct drm_crtc_helper_funcs *funcs;
  
  		funcs = crtc->helper_private;
  
  		if (!funcs || !funcs->atomic_check)
  			continue;
  
  		ret = funcs->atomic_check(crtc, state->crtc_states[i]);
  		if (ret) {
  			DRM_DEBUG_ATOMIC("[CRTC:%d] atomic driver check failed\n",
  					 crtc->base.id);
  			return ret;
  		}
  	}
  
  	return ret;
  }
  EXPORT_SYMBOL(drm_atomic_helper_check_planes);
  
  /**
   * drm_atomic_helper_check - validate state object
   * @dev: DRM device
   * @state: the driver state object
   *
   * Check the state object to see if the requested state is physically possible.
   * Only crtcs and planes have check callbacks, so for any additional (global)
   * checking that a driver needs it can simply wrap that around this function.
   * Drivers without such needs can directly use this as their ->atomic_check()
   * callback.
   *
   * This just wraps the two parts of the state checking for planes and modeset
   * state in the default order: First it calls drm_atomic_helper_check_modeset()
   * and then drm_atomic_helper_check_planes(). The assumption is that the
   * ->atomic_check functions depend upon an updated adjusted_mode.clock to
   * e.g. properly compute watermarks.
   *
   * RETURNS
   * Zero for success or -errno
   */
  int drm_atomic_helper_check(struct drm_device *dev,
  			    struct drm_atomic_state *state)
  {
  	int ret;
  
  	ret = drm_atomic_helper_check_modeset(dev, state);
  	if (ret)
  		return ret;
  
  	ret = drm_atomic_helper_check_planes(dev, state);
  	if (ret)
  		return ret;
  
  	return ret;
  }
  EXPORT_SYMBOL(drm_atomic_helper_check);
  
  static void
  disable_outputs(struct drm_device *dev, struct drm_atomic_state *old_state)
  {
  	struct drm_connector *connector;
  	struct drm_connector_state *old_conn_state;
  	struct drm_crtc *crtc;
  	struct drm_crtc_state *old_crtc_state;
  	int i;
  
  	for_each_connector_in_state(old_state, connector, old_conn_state, i) {
  		const struct drm_encoder_helper_funcs *funcs;
  		struct drm_encoder *encoder;
  		struct drm_crtc_state *old_crtc_state;
  
  		/* Shut down everything that's in the changeset and currently
  		 * still on. So need to check the old, saved state. */
  		if (!old_conn_state->crtc)
  			continue;
  
  		old_crtc_state = old_state->crtc_states[drm_crtc_index(old_conn_state->crtc)];
  
  		if (!old_crtc_state->active)
  			continue;
  
  		encoder = old_conn_state->best_encoder;
  
  		/* We shouldn't get this far if we didn't previously have
  		 * an encoder.. but WARN_ON() rather than explode.
  		 */
  		if (WARN_ON(!encoder))
  			continue;
  
  		funcs = encoder->helper_private;
  
  		DRM_DEBUG_ATOMIC("disabling [ENCODER:%d:%s]\n",
  				 encoder->base.id, encoder->name);
  
  		/*
  		 * Each encoder has at most one connector (since we always steal
  		 * it away), so we won't call call disable hooks twice.
  		 */
  		if (encoder->bridge)
  			encoder->bridge->funcs->disable(encoder->bridge);
  
  		/* Right function depends upon target state. */
  		if (connector->state->crtc && funcs->prepare)
  			funcs->prepare(encoder);
  		else if (funcs->disable)
  			funcs->disable(encoder);
  		else
  			funcs->dpms(encoder, DRM_MODE_DPMS_OFF);
  
  		if (encoder->bridge)
  			encoder->bridge->funcs->post_disable(encoder->bridge);
  	}
  
  	for_each_crtc_in_state(old_state, crtc, old_crtc_state, i) {
  		const struct drm_crtc_helper_funcs *funcs;
  
  		/* Shut down everything that needs a full modeset. */
  		if (!needs_modeset(crtc->state))
  			continue;
  
  		if (!old_crtc_state->active)
  			continue;
  
  		funcs = crtc->helper_private;
  
  		DRM_DEBUG_ATOMIC("disabling [CRTC:%d]\n",
  				 crtc->base.id);
  
  
  		/* Right function depends upon target state. */
  		if (crtc->state->enable && funcs->prepare)
  			funcs->prepare(crtc);
  		else if (funcs->disable)
  			funcs->disable(crtc);
  		else
  			funcs->dpms(crtc, DRM_MODE_DPMS_OFF);
  	}
  }
  
  static void
  set_routing_links(struct drm_device *dev, struct drm_atomic_state *old_state)
  {
  	struct drm_connector *connector;
  	struct drm_connector_state *old_conn_state;
  	struct drm_crtc *crtc;
  	struct drm_crtc_state *old_crtc_state;
  	int i;
  
  	/* clear out existing links */
  	for_each_connector_in_state(old_state, connector, old_conn_state, i) {
  		if (!connector->encoder)
  			continue;
  
  		WARN_ON(!connector->encoder->crtc);
  
  		connector->encoder->crtc = NULL;
  		connector->encoder = NULL;
  	}
  
  	/* set new links */
  	for_each_connector_in_state(old_state, connector, old_conn_state, i) {
  		if (!connector->state->crtc)
  			continue;
  
  		if (WARN_ON(!connector->state->best_encoder))
  			continue;
  
  		connector->encoder = connector->state->best_encoder;
  		connector->encoder->crtc = connector->state->crtc;
  	}
  
  	/* set legacy state in the crtc structure */
  	for_each_crtc_in_state(old_state, crtc, old_crtc_state, i) {
  		crtc->mode = crtc->state->mode;
  		crtc->enabled = crtc->state->enable;
  		crtc->x = crtc->primary->state->src_x >> 16;
  		crtc->y = crtc->primary->state->src_y >> 16;
  	}
  }
  
  static void
  crtc_set_mode(struct drm_device *dev, struct drm_atomic_state *old_state)
  {
  	struct drm_crtc *crtc;
  	struct drm_crtc_state *old_crtc_state;
  	struct drm_connector *connector;
  	struct drm_connector_state *old_conn_state;
  	int i;
  
  	for_each_crtc_in_state(old_state, crtc, old_crtc_state, i) {
  		const struct drm_crtc_helper_funcs *funcs;
  
  		if (!crtc->state->mode_changed)
  			continue;
  
  		funcs = crtc->helper_private;
  
  		if (crtc->state->enable && funcs->mode_set_nofb) {
  			DRM_DEBUG_ATOMIC("modeset on [CRTC:%d]\n",
  					 crtc->base.id);
  
  			funcs->mode_set_nofb(crtc);
  		}
  	}
  
  	for_each_connector_in_state(old_state, connector, old_conn_state, i) {
  		const struct drm_encoder_helper_funcs *funcs;
  		struct drm_crtc_state *new_crtc_state;
  		struct drm_encoder *encoder;
  		struct drm_display_mode *mode, *adjusted_mode;
  
  		if (!connector->state->best_encoder)
  			continue;
  
  		encoder = connector->state->best_encoder;
  		funcs = encoder->helper_private;
  		new_crtc_state = connector->state->crtc->state;
  		mode = &new_crtc_state->mode;
  		adjusted_mode = &new_crtc_state->adjusted_mode;
  
  		if (!new_crtc_state->mode_changed)
  			continue;
  
  		DRM_DEBUG_ATOMIC("modeset on [ENCODER:%d:%s]\n",
  				 encoder->base.id, encoder->name);
  
  		/*
  		 * Each encoder has at most one connector (since we always steal
  		 * it away), so we won't call call mode_set hooks twice.
  		 */
  		if (funcs->mode_set)
  			funcs->mode_set(encoder, mode, adjusted_mode);
  
  		if (encoder->bridge && encoder->bridge->funcs->mode_set)
  			encoder->bridge->funcs->mode_set(encoder->bridge,
  							 mode, adjusted_mode);
  	}
  }
  
  /**
   * drm_atomic_helper_commit_modeset_disables - modeset commit to disable outputs
   * @dev: DRM device
   * @old_state: atomic state object with old state structures
   *
   * This function shuts down all the outputs that need to be shut down and
   * prepares them (if required) with the new mode.
   *
   * For compatability with legacy crtc helpers this should be called before
   * drm_atomic_helper_commit_planes(), which is what the default commit function
   * does. But drivers with different needs can group the modeset commits together
   * and do the plane commits at the end. This is useful for drivers doing runtime
   * PM since planes updates then only happen when the CRTC is actually enabled.
   */
  void drm_atomic_helper_commit_modeset_disables(struct drm_device *dev,
  					       struct drm_atomic_state *old_state)
  {
  	disable_outputs(dev, old_state);
  	set_routing_links(dev, old_state);
  	crtc_set_mode(dev, old_state);
  }
  EXPORT_SYMBOL(drm_atomic_helper_commit_modeset_disables);
  
  /**
   * drm_atomic_helper_commit_modeset_enables - modeset commit to enable outputs
   * @dev: DRM device
   * @old_state: atomic state object with old state structures
   *
   * This function enables all the outputs with the new configuration which had to
   * be turned off for the update.
   *
   * For compatability with legacy crtc helpers this should be called after
   * drm_atomic_helper_commit_planes(), which is what the default commit function
   * does. But drivers with different needs can group the modeset commits together
   * and do the plane commits at the end. This is useful for drivers doing runtime
   * PM since planes updates then only happen when the CRTC is actually enabled.
   */
  void drm_atomic_helper_commit_modeset_enables(struct drm_device *dev,
  					      struct drm_atomic_state *old_state)
  {
  	struct drm_crtc *crtc;
  	struct drm_crtc_state *old_crtc_state;
  	struct drm_connector *connector;
  	struct drm_connector_state *old_conn_state;
  	int i;
  
  	for_each_crtc_in_state(old_state, crtc, old_crtc_state, i) {
  		const struct drm_crtc_helper_funcs *funcs;
  
  		/* Need to filter out CRTCs where only planes change. */
  		if (!needs_modeset(crtc->state))
  			continue;
  
  		if (!crtc->state->active)
  			continue;
  
  		funcs = crtc->helper_private;
  
  		if (crtc->state->enable) {
  			DRM_DEBUG_ATOMIC("enabling [CRTC:%d]\n",
  					 crtc->base.id);
  
  			if (funcs->enable)
  				funcs->enable(crtc);
  			else
  				funcs->commit(crtc);
  		}
  	}
  
  	for_each_connector_in_state(old_state, connector, old_conn_state, i) {
  		const struct drm_encoder_helper_funcs *funcs;
  		struct drm_encoder *encoder;
  
  		if (!connector->state->best_encoder)
  			continue;
  
  		if (!connector->state->crtc->state->active)
  			continue;
  
  		encoder = connector->state->best_encoder;
  		funcs = encoder->helper_private;
  
  		DRM_DEBUG_ATOMIC("enabling [ENCODER:%d:%s]\n",
  				 encoder->base.id, encoder->name);
  
  		/*
  		 * Each encoder has at most one connector (since we always steal
  		 * it away), so we won't call call enable hooks twice.
  		 */
  		if (encoder->bridge)
  			encoder->bridge->funcs->pre_enable(encoder->bridge);
  
  		if (funcs->enable)
  			funcs->enable(encoder);
  		else
  			funcs->commit(encoder);
  
  		if (encoder->bridge)
  			encoder->bridge->funcs->enable(encoder->bridge);
  	}
  }
  EXPORT_SYMBOL(drm_atomic_helper_commit_modeset_enables);
  
  static void wait_for_fences(struct drm_device *dev,
  			    struct drm_atomic_state *state)
  {
  	struct drm_plane *plane;
  	struct drm_plane_state *plane_state;
  	int i;
  
  	for_each_plane_in_state(state, plane, plane_state, i) {
  		if (!plane->state->fence)
  			continue;
  
  		WARN_ON(!plane->state->fb);
  
  		fence_wait(plane->state->fence, false);
  		fence_put(plane->state->fence);
  		plane->state->fence = NULL;
  	}
  }
  
  static bool framebuffer_changed(struct drm_device *dev,
  				struct drm_atomic_state *old_state,
  				struct drm_crtc *crtc)
  {
  	struct drm_plane *plane;
  	struct drm_plane_state *old_plane_state;
  	int i;
  
  	for_each_plane_in_state(old_state, plane, old_plane_state, i) {
  		if (plane->state->crtc != crtc &&
  		    old_plane_state->crtc != crtc)
  			continue;
  
  		if (plane->state->fb != old_plane_state->fb)
  			return true;
  	}
  
  	return false;
  }
  
  /**
   * drm_atomic_helper_wait_for_vblanks - wait for vblank on crtcs
   * @dev: DRM device
   * @old_state: atomic state object with old state structures
   *
   * Helper to, after atomic commit, wait for vblanks on all effected
   * crtcs (ie. before cleaning up old framebuffers using
   * drm_atomic_helper_cleanup_planes()). It will only wait on crtcs where the
   * framebuffers have actually changed to optimize for the legacy cursor and
   * plane update use-case.
   */
  void
  drm_atomic_helper_wait_for_vblanks(struct drm_device *dev,
  		struct drm_atomic_state *old_state)
  {
  	struct drm_crtc *crtc;
  	struct drm_crtc_state *old_crtc_state;
  	int i, ret;
  
  	for_each_crtc_in_state(old_state, crtc, old_crtc_state, i) {
  		/* No one cares about the old state, so abuse it for tracking
  		 * and store whether we hold a vblank reference (and should do a
  		 * vblank wait) in the ->enable boolean. */
  		old_crtc_state->enable = false;
  
  		if (!crtc->state->enable)
  			continue;
  
  		/* Legacy cursor ioctls are completely unsynced, and userspace
  		 * relies on that (by doing tons of cursor updates). */
  		if (old_state->legacy_cursor_update)
  			continue;
  
  		if (!framebuffer_changed(dev, old_state, crtc))
  			continue;
  
  		ret = drm_crtc_vblank_get(crtc);
  		if (ret != 0)
  			continue;
  
  		old_crtc_state->enable = true;
  		old_crtc_state->last_vblank_count = drm_vblank_count(dev, i);
  	}
  
  	for_each_crtc_in_state(old_state, crtc, old_crtc_state, i) {
  		if (!old_crtc_state->enable)
  			continue;
  
  		ret = wait_event_timeout(dev->vblank[i].queue,
  				old_crtc_state->last_vblank_count !=
  					drm_vblank_count(dev, i),
  				msecs_to_jiffies(50));
  
  		drm_crtc_vblank_put(crtc);
  	}
  }
  EXPORT_SYMBOL(drm_atomic_helper_wait_for_vblanks);
  
  /**
   * drm_atomic_helper_commit - commit validated state object
   * @dev: DRM device
   * @state: the driver state object
   * @async: asynchronous commit
   *
   * This function commits a with drm_atomic_helper_check() pre-validated state
   * object. This can still fail when e.g. the framebuffer reservation fails. For
   * now this doesn't implement asynchronous commits.
   *
   * RETURNS
   * Zero for success or -errno.
   */
  int drm_atomic_helper_commit(struct drm_device *dev,
  			     struct drm_atomic_state *state,
  			     bool async)
  {
  	int ret;
  
  	if (async)
  		return -EBUSY;
  
  	ret = drm_atomic_helper_prepare_planes(dev, state);
  	if (ret)
  		return ret;
  
  	/*
  	 * This is the point of no return - everything below never fails except
  	 * when the hw goes bonghits. Which means we can commit the new state on
  	 * the software side now.
  	 */
  
  	drm_atomic_helper_swap_state(dev, state);
  
  	/*
  	 * Everything below can be run asynchronously without the need to grab
  	 * any modeset locks at all under one conditions: It must be guaranteed
  	 * that the asynchronous work has either been cancelled (if the driver
  	 * supports it, which at least requires that the framebuffers get
  	 * cleaned up with drm_atomic_helper_cleanup_planes()) or completed
  	 * before the new state gets committed on the software side with
  	 * drm_atomic_helper_swap_state().
  	 *
  	 * This scheme allows new atomic state updates to be prepared and
  	 * checked in parallel to the asynchronous completion of the previous
  	 * update. Which is important since compositors need to figure out the
  	 * composition of the next frame right after having submitted the
  	 * current layout.
  	 */
  
  	wait_for_fences(dev, state);
  
  	drm_atomic_helper_commit_modeset_disables(dev, state);
  
  	drm_atomic_helper_commit_planes(dev, state);
  
  	drm_atomic_helper_commit_modeset_enables(dev, state);
  
  	drm_atomic_helper_wait_for_vblanks(dev, state);
  
  	drm_atomic_helper_cleanup_planes(dev, state);
  
  	drm_atomic_state_free(state);
  
  	return 0;
  }
  EXPORT_SYMBOL(drm_atomic_helper_commit);
  
  /**
   * DOC: implementing async commit
   *
   * For now the atomic helpers don't support async commit directly. If there is
   * real need it could be added though, using the dma-buf fence infrastructure
   * for generic synchronization with outstanding rendering.
   *
   * For now drivers have to implement async commit themselves, with the following
   * sequence being the recommended one:
   *
   * 1. Run drm_atomic_helper_prepare_planes() first. This is the only function
   * which commit needs to call which can fail, so we want to run it first and
   * synchronously.
   *
   * 2. Synchronize with any outstanding asynchronous commit worker threads which
   * might be affected the new state update. This can be done by either cancelling
   * or flushing the work items, depending upon whether the driver can deal with
   * cancelled updates. Note that it is important to ensure that the framebuffer
   * cleanup is still done when cancelling.
   *
   * For sufficient parallelism it is recommended to have a work item per crtc
   * (for updates which don't touch global state) and a global one. Then we only
   * need to synchronize with the crtc work items for changed crtcs and the global
   * work item, which allows nice concurrent updates on disjoint sets of crtcs.
   *
   * 3. The software state is updated synchronously with
   * drm_atomic_helper_swap_state. Doing this under the protection of all modeset
   * locks means concurrent callers never see inconsistent state. And doing this
   * while it's guaranteed that no relevant async worker runs means that async
   * workers do not need grab any locks. Actually they must not grab locks, for
   * otherwise the work flushing will deadlock.
   *
   * 4. Schedule a work item to do all subsequent steps, using the split-out
   * commit helpers: a) pre-plane commit b) plane commit c) post-plane commit and
   * then cleaning up the framebuffers after the old framebuffer is no longer
   * being displayed.
   */
  
  /**
   * drm_atomic_helper_prepare_planes - prepare plane resources after commit
   * @dev: DRM device
   * @state: atomic state object with old state structures
   *
   * This function prepares plane state, specifically framebuffers, for the new
   * configuration. If any failure is encountered this function will call
   * ->cleanup_fb on any already successfully prepared framebuffer.
   *
   * Returns:
   * 0 on success, negative error code on failure.
   */
  int drm_atomic_helper_prepare_planes(struct drm_device *dev,
  				     struct drm_atomic_state *state)
  {
  	int nplanes = dev->mode_config.num_total_plane;
  	int ret, i;
  
  	for (i = 0; i < nplanes; i++) {
  		const struct drm_plane_helper_funcs *funcs;
  		struct drm_plane *plane = state->planes[i];
  		struct drm_framebuffer *fb;
  
  		if (!plane)
  			continue;
  
  		funcs = plane->helper_private;
  
  		fb = state->plane_states[i]->fb;
  
  		if (fb && funcs->prepare_fb) {
  			ret = funcs->prepare_fb(plane, fb);
  			if (ret)
  				goto fail;
  		}
  	}
  
  	return 0;
  
  fail:
  	for (i--; i >= 0; i--) {
  		const struct drm_plane_helper_funcs *funcs;
  		struct drm_plane *plane = state->planes[i];
  		struct drm_framebuffer *fb;
  
  		if (!plane)
  			continue;
  
  		funcs = plane->helper_private;
  
  		fb = state->plane_states[i]->fb;
  
  		if (fb && funcs->cleanup_fb)
  			funcs->cleanup_fb(plane, fb);
  
  	}
  
  	return ret;
  }
  EXPORT_SYMBOL(drm_atomic_helper_prepare_planes);
  
  /**
   * drm_atomic_helper_commit_planes - commit plane state
   * @dev: DRM device
   * @old_state: atomic state object with old state structures
   *
   * This function commits the new plane state using the plane and atomic helper
   * functions for planes and crtcs. It assumes that the atomic state has already
   * been pushed into the relevant object state pointers, since this step can no
   * longer fail.
   *
   * It still requires the global state object @old_state to know which planes and
   * crtcs need to be updated though.
   */
  void drm_atomic_helper_commit_planes(struct drm_device *dev,
  				     struct drm_atomic_state *old_state)
  {
  	struct drm_crtc *crtc;
  	struct drm_crtc_state *old_crtc_state;
  	struct drm_plane *plane;
  	struct drm_plane_state *old_plane_state;
  	int i;
  
  	for_each_crtc_in_state(old_state, crtc, old_crtc_state, i) {
  		const struct drm_crtc_helper_funcs *funcs;
  
  		funcs = crtc->helper_private;
  
  		if (!funcs || !funcs->atomic_begin)
  			continue;
  
  		funcs->atomic_begin(crtc);
  	}
  
  	for_each_plane_in_state(old_state, plane, old_plane_state, i) {
  		const struct drm_plane_helper_funcs *funcs;
  
  		funcs = plane->helper_private;
  
  		if (!funcs)
  			continue;
  
  		old_plane_state = old_state->plane_states[i];
  
  		/*
  		 * Special-case disabling the plane if drivers support it.
  		 */
  		if (drm_atomic_plane_disabling(plane, old_plane_state) &&
  		    funcs->atomic_disable)
  			funcs->atomic_disable(plane, old_plane_state);
  		else
  			funcs->atomic_update(plane, old_plane_state);
  	}
  
  	for_each_crtc_in_state(old_state, crtc, old_crtc_state, i) {
  		const struct drm_crtc_helper_funcs *funcs;
  
  		funcs = crtc->helper_private;
  
  		if (!funcs || !funcs->atomic_flush)
  			continue;
  
  		funcs->atomic_flush(crtc);
  	}
  }
  EXPORT_SYMBOL(drm_atomic_helper_commit_planes);
  
  /**
   * drm_atomic_helper_cleanup_planes - cleanup plane resources after commit
   * @dev: DRM device
   * @old_state: atomic state object with old state structures
   *
   * This function cleans up plane state, specifically framebuffers, from the old
   * configuration. Hence the old configuration must be perserved in @old_state to
   * be able to call this function.
   *
   * This function must also be called on the new state when the atomic update
   * fails at any point after calling drm_atomic_helper_prepare_planes().
   */
  void drm_atomic_helper_cleanup_planes(struct drm_device *dev,
  				      struct drm_atomic_state *old_state)
  {
  	struct drm_plane *plane;
  	struct drm_plane_state *plane_state;
  	int i;
  
  	for_each_plane_in_state(old_state, plane, plane_state, i) {
  		const struct drm_plane_helper_funcs *funcs;
  		struct drm_framebuffer *old_fb;
  
  		funcs = plane->helper_private;
  
  		old_fb = old_state->plane_states[i]->fb;
  
  		if (old_fb && funcs->cleanup_fb)
  			funcs->cleanup_fb(plane, old_fb);
  	}
  }
  EXPORT_SYMBOL(drm_atomic_helper_cleanup_planes);
  
  /**
   * drm_atomic_helper_swap_state - store atomic state into current sw state
   * @dev: DRM device
   * @state: atomic state
   *
   * This function stores the atomic state into the current state pointers in all
   * driver objects. It should be called after all failing steps have been done
   * and succeeded, but before the actual hardware state is committed.
   *
   * For cleanup and error recovery the current state for all changed objects will
   * be swaped into @state.
   *
   * With that sequence it fits perfectly into the plane prepare/cleanup sequence:
   *
   * 1. Call drm_atomic_helper_prepare_planes() with the staged atomic state.
   *
   * 2. Do any other steps that might fail.
   *
   * 3. Put the staged state into the current state pointers with this function.
   *
   * 4. Actually commit the hardware state.
   *
   * 5. Call drm_atomic_helper_cleanup_planes with @state, which since step 3
   * contains the old state. Also do any other cleanup required with that state.
   */
  void drm_atomic_helper_swap_state(struct drm_device *dev,
  				  struct drm_atomic_state *state)
  {
  	int i;
  
  	for (i = 0; i < dev->mode_config.num_connector; i++) {
  		struct drm_connector *connector = state->connectors[i];
  
  		if (!connector)
  			continue;
  
  		connector->state->state = state;
  		swap(state->connector_states[i], connector->state);
  		connector->state->state = NULL;
  	}
  
  	for (i = 0; i < dev->mode_config.num_crtc; i++) {
  		struct drm_crtc *crtc = state->crtcs[i];
  
  		if (!crtc)
  			continue;
  
  		crtc->state->state = state;
  		swap(state->crtc_states[i], crtc->state);
  		crtc->state->state = NULL;
  	}
  
  	for (i = 0; i < dev->mode_config.num_total_plane; i++) {
  		struct drm_plane *plane = state->planes[i];
  
  		if (!plane)
  			continue;
  
  		plane->state->state = state;
  		swap(state->plane_states[i], plane->state);
  		plane->state->state = NULL;
  	}
  }
  EXPORT_SYMBOL(drm_atomic_helper_swap_state);
  
  /**
   * drm_atomic_helper_update_plane - Helper for primary plane update using atomic
   * @plane: plane object to update
   * @crtc: owning CRTC of owning plane
   * @fb: framebuffer to flip onto plane
   * @crtc_x: x offset of primary plane on crtc
   * @crtc_y: y offset of primary plane on crtc
   * @crtc_w: width of primary plane rectangle on crtc
   * @crtc_h: height of primary plane rectangle on crtc
   * @src_x: x offset of @fb for panning
   * @src_y: y offset of @fb for panning
   * @src_w: width of source rectangle in @fb
   * @src_h: height of source rectangle in @fb
   *
   * Provides a default plane update handler using the atomic driver interface.
   *
   * RETURNS:
   * Zero on success, error code on failure
   */
  int drm_atomic_helper_update_plane(struct drm_plane *plane,
  				   struct drm_crtc *crtc,
  				   struct drm_framebuffer *fb,
  				   int crtc_x, int crtc_y,
  				   unsigned int crtc_w, unsigned int crtc_h,
  				   uint32_t src_x, uint32_t src_y,
  				   uint32_t src_w, uint32_t src_h)
  {
  	struct drm_atomic_state *state;
  	struct drm_plane_state *plane_state;
  	int ret = 0;
  
  	state = drm_atomic_state_alloc(plane->dev);
  	if (!state)
  		return -ENOMEM;
  
  	state->acquire_ctx = drm_modeset_legacy_acquire_ctx(crtc);
  retry:
  	plane_state = drm_atomic_get_plane_state(state, plane);
  	if (IS_ERR(plane_state)) {
  		ret = PTR_ERR(plane_state);
  		goto fail;
  	}
  
  	ret = drm_atomic_set_crtc_for_plane(plane_state, crtc);
  	if (ret != 0)
  		goto fail;
  	drm_atomic_set_fb_for_plane(plane_state, fb);
  	plane_state->crtc_x = crtc_x;
  	plane_state->crtc_y = crtc_y;
  	plane_state->crtc_h = crtc_h;
  	plane_state->crtc_w = crtc_w;
  	plane_state->src_x = src_x;
  	plane_state->src_y = src_y;
  	plane_state->src_h = src_h;
  	plane_state->src_w = src_w;
  
  	if (plane == crtc->cursor)
  		state->legacy_cursor_update = true;
  
  	ret = drm_atomic_commit(state);
  	if (ret != 0)
  		goto fail;
  
  	/* Driver takes ownership of state on successful commit. */
  	return 0;
  fail:
  	if (ret == -EDEADLK)
  		goto backoff;
  
  	drm_atomic_state_free(state);
  
  	return ret;
  backoff:
  	drm_atomic_state_clear(state);
  	drm_atomic_legacy_backoff(state);
  
  	/*
  	 * Someone might have exchanged the framebuffer while we dropped locks
  	 * in the backoff code. We need to fix up the fb refcount tracking the
  	 * core does for us.
  	 */
  	plane->old_fb = plane->fb;
  
  	goto retry;
  }
  EXPORT_SYMBOL(drm_atomic_helper_update_plane);
  
  /**
   * drm_atomic_helper_disable_plane - Helper for primary plane disable using * atomic
   * @plane: plane to disable
   *
   * Provides a default plane disable handler using the atomic driver interface.
   *
   * RETURNS:
   * Zero on success, error code on failure
   */
  int drm_atomic_helper_disable_plane(struct drm_plane *plane)
  {
  	struct drm_atomic_state *state;
  	struct drm_plane_state *plane_state;
  	int ret = 0;
  
  	/*
  	 * FIXME: Without plane->crtc set we can't get at the implicit legacy
  	 * acquire context. The real fix will be to wire the acquire ctx through
  	 * everywhere we need it, but meanwhile prevent chaos by just skipping
  	 * this noop. The critical case is the cursor ioctls which a) only grab
  	 * crtc/cursor-plane locks (so we need the crtc to get at the right
  	 * acquire context) and b) can try to disable the plane multiple times.
  	 */
  	if (!plane->crtc)
  		return 0;
  
  	state = drm_atomic_state_alloc(plane->dev);
  	if (!state)
  		return -ENOMEM;
  
  	state->acquire_ctx = drm_modeset_legacy_acquire_ctx(plane->crtc);
  retry:
  	plane_state = drm_atomic_get_plane_state(state, plane);
  	if (IS_ERR(plane_state)) {
  		ret = PTR_ERR(plane_state);
  		goto fail;
  	}
  
  	ret = drm_atomic_set_crtc_for_plane(plane_state, NULL);
  	if (ret != 0)
  		goto fail;
  	drm_atomic_set_fb_for_plane(plane_state, NULL);
  	plane_state->crtc_x = 0;
  	plane_state->crtc_y = 0;
  	plane_state->crtc_h = 0;
  	plane_state->crtc_w = 0;
  	plane_state->src_x = 0;
  	plane_state->src_y = 0;
  	plane_state->src_h = 0;
  	plane_state->src_w = 0;
  
  	if (plane == plane->crtc->cursor)
  		state->legacy_cursor_update = true;
  
  	ret = drm_atomic_commit(state);
  	if (ret != 0)
  		goto fail;
  
  	/* Driver takes ownership of state on successful commit. */
  	return 0;
  fail:
  	if (ret == -EDEADLK)
  		goto backoff;
  
  	drm_atomic_state_free(state);
  
  	return ret;
  backoff:
  	drm_atomic_state_clear(state);
  	drm_atomic_legacy_backoff(state);
  
  	/*
  	 * Someone might have exchanged the framebuffer while we dropped locks
  	 * in the backoff code. We need to fix up the fb refcount tracking the
  	 * core does for us.
  	 */
  	plane->old_fb = plane->fb;
  
  	goto retry;
  }
  EXPORT_SYMBOL(drm_atomic_helper_disable_plane);
  
  static int update_output_state(struct drm_atomic_state *state,
  			       struct drm_mode_set *set)
  {
  	struct drm_device *dev = set->crtc->dev;
  	struct drm_crtc *crtc;
  	struct drm_crtc_state *crtc_state;
  	struct drm_connector *connector;
  	struct drm_connector_state *conn_state;
  	int ret, i, j;
  
  	ret = drm_modeset_lock(&dev->mode_config.connection_mutex,
  			       state->acquire_ctx);
  	if (ret)
  		return ret;
  
  	/* First grab all affected connector/crtc states. */
  	for (i = 0; i < set->num_connectors; i++) {
  		conn_state = drm_atomic_get_connector_state(state,
  							    set->connectors[i]);
  		if (IS_ERR(conn_state))
  			return PTR_ERR(conn_state);
  	}
  
  	for_each_crtc_in_state(state, crtc, crtc_state, i) {
  		ret = drm_atomic_add_affected_connectors(state, crtc);
  		if (ret)
  			return ret;
  	}
  
  	/* Then recompute connector->crtc links and crtc enabling state. */
  	for_each_connector_in_state(state, connector, conn_state, i) {
  		if (conn_state->crtc == set->crtc) {
  			ret = drm_atomic_set_crtc_for_connector(conn_state,
  								NULL);
  			if (ret)
  				return ret;
  		}
  
  		for (j = 0; j < set->num_connectors; j++) {
  			if (set->connectors[j] == connector) {
  				ret = drm_atomic_set_crtc_for_connector(conn_state,
  									set->crtc);
  				if (ret)
  					return ret;
  				break;
  			}
  		}
  	}
  
  	for_each_crtc_in_state(state, crtc, crtc_state, i) {
  		/* Don't update ->enable for the CRTC in the set_config request,
  		 * since a mismatch would indicate a bug in the upper layers.
  		 * The actual modeset code later on will catch any
  		 * inconsistencies here. */
  		if (crtc == set->crtc)
  			continue;
  
  		crtc_state->enable =
  			drm_atomic_connectors_for_crtc(state, crtc);
  	}
  
  	return 0;
  }
  
  /**
   * drm_atomic_helper_set_config - set a new config from userspace
   * @set: mode set configuration
   *
   * Provides a default crtc set_config handler using the atomic driver interface.
   *
   * Returns:
   * Returns 0 on success, negative errno numbers on failure.
   */
  int drm_atomic_helper_set_config(struct drm_mode_set *set)
  {
  	struct drm_atomic_state *state;
  	struct drm_crtc *crtc = set->crtc;
  	struct drm_crtc_state *crtc_state;
  	struct drm_plane_state *primary_state;
  	int ret = 0;
  
  	state = drm_atomic_state_alloc(crtc->dev);
  	if (!state)
  		return -ENOMEM;
  
  	state->acquire_ctx = drm_modeset_legacy_acquire_ctx(crtc);
  retry:
  	crtc_state = drm_atomic_get_crtc_state(state, crtc);
  	if (IS_ERR(crtc_state)) {
  		ret = PTR_ERR(crtc_state);
  		goto fail;
  	}
  
  	primary_state = drm_atomic_get_plane_state(state, crtc->primary);
  	if (IS_ERR(primary_state)) {
  		ret = PTR_ERR(primary_state);
  		goto fail;
  	}
  
  	if (!set->mode) {
  		WARN_ON(set->fb);
  		WARN_ON(set->num_connectors);
  
  		ret = drm_atomic_set_mode_for_crtc(crtc_state, NULL);
  		if (ret != 0)
  			goto fail;
  
  		crtc_state->active = false;
  
  		ret = drm_atomic_set_crtc_for_plane(primary_state, NULL);
  		if (ret != 0)
  			goto fail;
  
  		drm_atomic_set_fb_for_plane(primary_state, NULL);
  
  		goto commit;
  	}
  
  	WARN_ON(!set->fb);
  	WARN_ON(!set->num_connectors);
  
  	ret = drm_atomic_set_mode_for_crtc(crtc_state, set->mode);
  	if (ret != 0)
  		goto fail;
  
  	crtc_state->active = true;
  
  	ret = drm_atomic_set_crtc_for_plane(primary_state, crtc);
  	if (ret != 0)
  		goto fail;
  	drm_atomic_set_fb_for_plane(primary_state, set->fb);
  	primary_state->crtc_x = 0;
  	primary_state->crtc_y = 0;
  	primary_state->crtc_h = set->mode->vdisplay;
  	primary_state->crtc_w = set->mode->hdisplay;
  	primary_state->src_x = set->x << 16;
  	primary_state->src_y = set->y << 16;
  	primary_state->src_h = set->mode->vdisplay << 16;
  	primary_state->src_w = set->mode->hdisplay << 16;
  
  commit:
  	ret = update_output_state(state, set);
  	if (ret)
  		goto fail;
  
  	ret = drm_atomic_commit(state);
  	if (ret != 0)
  		goto fail;
  
  	/* Driver takes ownership of state on successful commit. */
  	return 0;
  fail:
  	if (ret == -EDEADLK)
  		goto backoff;
  
  	drm_atomic_state_free(state);
  
  	return ret;
  backoff:
  	drm_atomic_state_clear(state);
  	drm_atomic_legacy_backoff(state);
  
  	/*
  	 * Someone might have exchanged the framebuffer while we dropped locks
  	 * in the backoff code. We need to fix up the fb refcount tracking the
  	 * core does for us.
  	 */
  	crtc->primary->old_fb = crtc->primary->fb;
  
  	goto retry;
  }
  EXPORT_SYMBOL(drm_atomic_helper_set_config);
  
  /**
   * drm_atomic_helper_crtc_set_property - helper for crtc prorties
   * @crtc: DRM crtc
   * @property: DRM property
   * @val: value of property
   *
   * Provides a default plane disablle handler using the atomic driver interface.
   *
   * RETURNS:
   * Zero on success, error code on failure
   */
  int
  drm_atomic_helper_crtc_set_property(struct drm_crtc *crtc,
  				    struct drm_property *property,
  				    uint64_t val)
  {
  	struct drm_atomic_state *state;
  	struct drm_crtc_state *crtc_state;
  	int ret = 0;
  
  	state = drm_atomic_state_alloc(crtc->dev);
  	if (!state)
  		return -ENOMEM;
  
  	/* ->set_property is always called with all locks held. */
  	state->acquire_ctx = crtc->dev->mode_config.acquire_ctx;
  retry:
  	crtc_state = drm_atomic_get_crtc_state(state, crtc);
  	if (IS_ERR(crtc_state)) {
  		ret = PTR_ERR(crtc_state);
  		goto fail;
  	}
  
  	ret = drm_atomic_crtc_set_property(crtc, crtc_state,
  			property, val);
  	if (ret)
  		goto fail;
  
  	ret = drm_atomic_commit(state);
  	if (ret != 0)
  		goto fail;
  
  	/* Driver takes ownership of state on successful commit. */
  	return 0;
  fail:
  	if (ret == -EDEADLK)
  		goto backoff;
  
  	drm_atomic_state_free(state);
  
  	return ret;
  backoff:
  	drm_atomic_state_clear(state);
  	drm_atomic_legacy_backoff(state);
  
  	goto retry;
  }
  EXPORT_SYMBOL(drm_atomic_helper_crtc_set_property);
  
  /**
   * drm_atomic_helper_plane_set_property - helper for plane prorties
   * @plane: DRM plane
   * @property: DRM property
   * @val: value of property
   *
   * Provides a default plane disable handler using the atomic driver interface.
   *
   * RETURNS:
   * Zero on success, error code on failure
   */
  int
  drm_atomic_helper_plane_set_property(struct drm_plane *plane,
  				    struct drm_property *property,
  				    uint64_t val)
  {
  	struct drm_atomic_state *state;
  	struct drm_plane_state *plane_state;
  	int ret = 0;
  
  	state = drm_atomic_state_alloc(plane->dev);
  	if (!state)
  		return -ENOMEM;
  
  	/* ->set_property is always called with all locks held. */
  	state->acquire_ctx = plane->dev->mode_config.acquire_ctx;
  retry:
  	plane_state = drm_atomic_get_plane_state(state, plane);
  	if (IS_ERR(plane_state)) {
  		ret = PTR_ERR(plane_state);
  		goto fail;
  	}
  
  	ret = drm_atomic_plane_set_property(plane, plane_state,
  			property, val);
  	if (ret)
  		goto fail;
  
  	ret = drm_atomic_commit(state);
  	if (ret != 0)
  		goto fail;
  
  	/* Driver takes ownership of state on successful commit. */
  	return 0;
  fail:
  	if (ret == -EDEADLK)
  		goto backoff;
  
  	drm_atomic_state_free(state);
  
  	return ret;
  backoff:
  	drm_atomic_state_clear(state);
  	drm_atomic_legacy_backoff(state);
  
  	goto retry;
  }
  EXPORT_SYMBOL(drm_atomic_helper_plane_set_property);
  
  /**
   * drm_atomic_helper_connector_set_property - helper for connector prorties
   * @connector: DRM connector
   * @property: DRM property
   * @val: value of property
   *
   * Provides a default plane disablle handler using the atomic driver interface.
   *
   * RETURNS:
   * Zero on success, error code on failure
   */
  int
  drm_atomic_helper_connector_set_property(struct drm_connector *connector,
  				    struct drm_property *property,
  				    uint64_t val)
  {
  	struct drm_atomic_state *state;
  	struct drm_connector_state *connector_state;
  	int ret = 0;
  
  	state = drm_atomic_state_alloc(connector->dev);
  	if (!state)
  		return -ENOMEM;
  
  	/* ->set_property is always called with all locks held. */
  	state->acquire_ctx = connector->dev->mode_config.acquire_ctx;
  retry:
  	connector_state = drm_atomic_get_connector_state(state, connector);
  	if (IS_ERR(connector_state)) {
  		ret = PTR_ERR(connector_state);
  		goto fail;
  	}
  
  	ret = drm_atomic_connector_set_property(connector, connector_state,
  			property, val);
  	if (ret)
  		goto fail;
  
  	ret = drm_atomic_commit(state);
  	if (ret != 0)
  		goto fail;
  
  	/* Driver takes ownership of state on successful commit. */
  	return 0;
  fail:
  	if (ret == -EDEADLK)
  		goto backoff;
  
  	drm_atomic_state_free(state);
  
  	return ret;
  backoff:
  	drm_atomic_state_clear(state);
  	drm_atomic_legacy_backoff(state);
  
  	goto retry;
  }
  EXPORT_SYMBOL(drm_atomic_helper_connector_set_property);
  
  /**
   * drm_atomic_helper_page_flip - execute a legacy page flip
   * @crtc: DRM crtc
   * @fb: DRM framebuffer
   * @event: optional DRM event to signal upon completion
   * @flags: flip flags for non-vblank sync'ed updates
   *
   * Provides a default page flip implementation using the atomic driver interface.
   *
   * Note that for now so called async page flips (i.e. updates which are not
   * synchronized to vblank) are not supported, since the atomic interfaces have
   * no provisions for this yet.
   *
   * Returns:
   * Returns 0 on success, negative errno numbers on failure.
   */
  int drm_atomic_helper_page_flip(struct drm_crtc *crtc,
  				struct drm_framebuffer *fb,
  				struct drm_pending_vblank_event *event,
  				uint32_t flags)
  {
  	struct drm_plane *plane = crtc->primary;
  	struct drm_atomic_state *state;
  	struct drm_plane_state *plane_state;
  	struct drm_crtc_state *crtc_state;
  	int ret = 0;
  
  	if (flags & DRM_MODE_PAGE_FLIP_ASYNC)
  		return -EINVAL;
  
  	state = drm_atomic_state_alloc(plane->dev);
  	if (!state)
  		return -ENOMEM;
  
  	state->acquire_ctx = drm_modeset_legacy_acquire_ctx(crtc);
  retry:
  	crtc_state = drm_atomic_get_crtc_state(state, crtc);
  	if (IS_ERR(crtc_state)) {
  		ret = PTR_ERR(crtc_state);
  		goto fail;
  	}
  	crtc_state->event = event;
  
  	plane_state = drm_atomic_get_plane_state(state, plane);
  	if (IS_ERR(plane_state)) {
  		ret = PTR_ERR(plane_state);
  		goto fail;
  	}
  
  	ret = drm_atomic_set_crtc_for_plane(plane_state, crtc);
  	if (ret != 0)
  		goto fail;
  	drm_atomic_set_fb_for_plane(plane_state, fb);
  
  	ret = drm_atomic_async_commit(state);
  	if (ret != 0)
  		goto fail;
  
  	/* TODO: ->page_flip is the only driver callback where the core
  	 * doesn't update plane->fb. For now patch it up here. */
  	plane->fb = plane->state->fb;
  
  	/* Driver takes ownership of state on successful async commit. */
  	return 0;
  fail:
  	if (ret == -EDEADLK)
  		goto backoff;
  
  	drm_atomic_state_free(state);
  
  	return ret;
  backoff:
  	drm_atomic_state_clear(state);
  	drm_atomic_legacy_backoff(state);
  
  	/*
  	 * Someone might have exchanged the framebuffer while we dropped locks
  	 * in the backoff code. We need to fix up the fb refcount tracking the
  	 * core does for us.
  	 */
  	plane->old_fb = plane->fb;
  
  	goto retry;
  }
  EXPORT_SYMBOL(drm_atomic_helper_page_flip);
  
  /**
   * drm_atomic_helper_connector_dpms() - connector dpms helper implementation
   * @connector: affected connector
   * @mode: DPMS mode
   *
   * This is the main helper function provided by the atomic helper framework for
   * implementing the legacy DPMS connector interface. It computes the new desired
   * ->active state for the corresponding CRTC (if the connector is enabled) and
   *  updates it.
   */
  void drm_atomic_helper_connector_dpms(struct drm_connector *connector,
  				      int mode)
  {
  	struct drm_mode_config *config = &connector->dev->mode_config;
  	struct drm_atomic_state *state;
  	struct drm_crtc_state *crtc_state;
  	struct drm_crtc *crtc;
  	struct drm_connector *tmp_connector;
  	int ret;
  	bool active = false;
  
  	if (mode != DRM_MODE_DPMS_ON)
  		mode = DRM_MODE_DPMS_OFF;
  
  	connector->dpms = mode;
  	crtc = connector->state->crtc;
  
  	if (!crtc)
  		return;
  
  	/* FIXME: ->dpms has no return value so can't forward the -ENOMEM. */
  	state = drm_atomic_state_alloc(connector->dev);
  	if (!state)
  		return;
  
  	state->acquire_ctx = drm_modeset_legacy_acquire_ctx(crtc);
  retry:
  	crtc_state = drm_atomic_get_crtc_state(state, crtc);
  	if (IS_ERR(crtc_state))
  		return;
  
  	WARN_ON(!drm_modeset_is_locked(&config->connection_mutex));
  
  	list_for_each_entry(tmp_connector, &config->connector_list, head) {
  		if (connector->state->crtc != crtc)
  			continue;
  
  		if (connector->dpms == DRM_MODE_DPMS_ON) {
  			active = true;
  			break;
  		}
  	}
  	crtc_state->active = active;
  
  	ret = drm_atomic_commit(state);
  	if (ret != 0)
  		goto fail;
  
  	/* Driver takes ownership of state on successful async commit. */
  	return;
  fail:
  	if (ret == -EDEADLK)
  		goto backoff;
  
  	drm_atomic_state_free(state);
  
  	WARN(1, "Driver bug: Changing ->active failed with ret=%i\n", ret);
  
  	return;
  backoff:
  	drm_atomic_state_clear(state);
  	drm_atomic_legacy_backoff(state);
  
  	goto retry;
  }
  EXPORT_SYMBOL(drm_atomic_helper_connector_dpms);
  
  /**
   * DOC: atomic state reset and initialization
   *
   * Both the drm core and the atomic helpers assume that there is always the full
   * and correct atomic software state for all connectors, CRTCs and planes
   * available. Which is a bit a problem on driver load and also after system
   * suspend. One way to solve this is to have a hardware state read-out
   * infrastructure which reconstructs the full software state (e.g. the i915
   * driver).
   *
   * The simpler solution is to just reset the software state to everything off,
   * which is easiest to do by calling drm_mode_config_reset(). To facilitate this
   * the atomic helpers provide default reset implementations for all hooks.
   */
  
  /**
   * drm_atomic_helper_crtc_reset - default ->reset hook for CRTCs
   * @crtc: drm CRTC
   *
   * Resets the atomic state for @crtc by freeing the state pointer (which might
   * be NULL, e.g. at driver load time) and allocating a new empty state object.
   */
  void drm_atomic_helper_crtc_reset(struct drm_crtc *crtc)
  {
  	if (crtc->state && crtc->state->mode_blob)
  		drm_property_unreference_blob(crtc->state->mode_blob);
  	kfree(crtc->state);
  	crtc->state = kzalloc(sizeof(*crtc->state), GFP_KERNEL);
  
  	if (crtc->state)
  		crtc->state->crtc = crtc;
  }
  EXPORT_SYMBOL(drm_atomic_helper_crtc_reset);
  
  /**
   * __drm_atomic_helper_crtc_duplicate_state - copy atomic CRTC state
   * @crtc: CRTC object
   * @state: atomic CRTC state
   *
   * Copies atomic state from a CRTC's current state and resets inferred values.
   * This is useful for drivers that subclass the CRTC state.
   */
  void __drm_atomic_helper_crtc_duplicate_state(struct drm_crtc *crtc,
  					      struct drm_crtc_state *state)
  {
  	memcpy(state, crtc->state, sizeof(*state));
  
  	if (state->mode_blob)
  		drm_property_reference_blob(state->mode_blob);
  	state->mode_changed = false;
  	state->active_changed = false;
  	state->planes_changed = false;
  	state->event = NULL;
  }
  EXPORT_SYMBOL(__drm_atomic_helper_crtc_duplicate_state);
  
  /**
   * drm_atomic_helper_crtc_duplicate_state - default state duplicate hook
   * @crtc: drm CRTC
   *
   * Default CRTC state duplicate hook for drivers which don't have their own
   * subclassed CRTC state structure.
   */
  struct drm_crtc_state *
  drm_atomic_helper_crtc_duplicate_state(struct drm_crtc *crtc)
  {
  	struct drm_crtc_state *state;
  
  	if (WARN_ON(!crtc->state))
  		return NULL;
  
  	state = kmalloc(sizeof(*state), GFP_KERNEL);
  	if (state)
  		__drm_atomic_helper_crtc_duplicate_state(crtc, state);
  
  	return state;
  }
  EXPORT_SYMBOL(drm_atomic_helper_crtc_duplicate_state);
  
  /**
   * __drm_atomic_helper_crtc_destroy_state - release CRTC state
   * @crtc: CRTC object
   * @state: CRTC state object to release
   *
   * Releases all resources stored in the CRTC state without actually freeing
   * the memory of the CRTC state. This is useful for drivers that subclass the
   * CRTC state.
   */
  void __drm_atomic_helper_crtc_destroy_state(struct drm_crtc *crtc,
  					    struct drm_crtc_state *state)
  {
  	if (state->mode_blob)
  		drm_property_unreference_blob(state->mode_blob);
  }
  EXPORT_SYMBOL(__drm_atomic_helper_crtc_destroy_state);
  
  /**
   * drm_atomic_helper_crtc_destroy_state - default state destroy hook
   * @crtc: drm CRTC
   * @state: CRTC state object to release
   *
   * Default CRTC state destroy hook for drivers which don't have their own
   * subclassed CRTC state structure.
   */
  void drm_atomic_helper_crtc_destroy_state(struct drm_crtc *crtc,
  					  struct drm_crtc_state *state)
  {
  	__drm_atomic_helper_crtc_destroy_state(crtc, state);
  	kfree(state);
  }
  EXPORT_SYMBOL(drm_atomic_helper_crtc_destroy_state);
  
  /**
   * drm_atomic_helper_plane_reset - default ->reset hook for planes
   * @plane: drm plane
   *
   * Resets the atomic state for @plane by freeing the state pointer (which might
   * be NULL, e.g. at driver load time) and allocating a new empty state object.
   */
  void drm_atomic_helper_plane_reset(struct drm_plane *plane)
  {
  	if (plane->state && plane->state->fb)
  		drm_framebuffer_unreference(plane->state->fb);
  
  	kfree(plane->state);
  	plane->state = kzalloc(sizeof(*plane->state), GFP_KERNEL);
  
  	if (plane->state)
  		plane->state->plane = plane;
  }
  EXPORT_SYMBOL(drm_atomic_helper_plane_reset);
  
  /**
   * __drm_atomic_helper_plane_duplicate_state - copy atomic plane state
   * @plane: plane object
   * @state: atomic plane state
   *
   * Copies atomic state from a plane's current state. This is useful for
   * drivers that subclass the plane state.
   */
  void __drm_atomic_helper_plane_duplicate_state(struct drm_plane *plane,
  					       struct drm_plane_state *state)
  {
  	memcpy(state, plane->state, sizeof(*state));
  
  	if (state->fb)
  		drm_framebuffer_reference(state->fb);
  }
  EXPORT_SYMBOL(__drm_atomic_helper_plane_duplicate_state);
  
  /**
   * drm_atomic_helper_plane_duplicate_state - default state duplicate hook
   * @plane: drm plane
   *
   * Default plane state duplicate hook for drivers which don't have their own
   * subclassed plane state structure.
   */
  struct drm_plane_state *
  drm_atomic_helper_plane_duplicate_state(struct drm_plane *plane)
  {
  	struct drm_plane_state *state;
  
  	if (WARN_ON(!plane->state))
  		return NULL;
  
  	state = kmalloc(sizeof(*state), GFP_KERNEL);
  	if (state)
  		__drm_atomic_helper_plane_duplicate_state(plane, state);
  
  	return state;
  }
  EXPORT_SYMBOL(drm_atomic_helper_plane_duplicate_state);
  
  /**
   * __drm_atomic_helper_plane_destroy_state - release plane state
   * @plane: plane object
   * @state: plane state object to release
   *
   * Releases all resources stored in the plane state without actually freeing
   * the memory of the plane state. This is useful for drivers that subclass the
   * plane state.
   */
  void __drm_atomic_helper_plane_destroy_state(struct drm_plane *plane,
  					     struct drm_plane_state *state)
  {
  	if (state->fb)
  		drm_framebuffer_unreference(state->fb);
  }
  EXPORT_SYMBOL(__drm_atomic_helper_plane_destroy_state);
  
  /**
   * drm_atomic_helper_plane_destroy_state - default state destroy hook
   * @plane: drm plane
   * @state: plane state object to release
   *
   * Default plane state destroy hook for drivers which don't have their own
   * subclassed plane state structure.
   */
  void drm_atomic_helper_plane_destroy_state(struct drm_plane *plane,
  					   struct drm_plane_state *state)
  {
  	__drm_atomic_helper_plane_destroy_state(plane, state);
  	kfree(state);
  }
  EXPORT_SYMBOL(drm_atomic_helper_plane_destroy_state);
  
  /**
   * drm_atomic_helper_connector_reset - default ->reset hook for connectors
   * @connector: drm connector
   *
   * Resets the atomic state for @connector by freeing the state pointer (which
   * might be NULL, e.g. at driver load time) and allocating a new empty state
   * object.
   */
  void drm_atomic_helper_connector_reset(struct drm_connector *connector)
  {
  	kfree(connector->state);
  	connector->state = kzalloc(sizeof(*connector->state), GFP_KERNEL);
  
  	if (connector->state)
  		connector->state->connector = connector;
  }
  EXPORT_SYMBOL(drm_atomic_helper_connector_reset);
  
  /**
   * __drm_atomic_helper_connector_duplicate_state - copy atomic connector state
   * @connector: connector object
   * @state: atomic connector state
   *
   * Copies atomic state from a connector's current state. This is useful for
   * drivers that subclass the connector state.
   */
  void
  __drm_atomic_helper_connector_duplicate_state(struct drm_connector *connector,
  					    struct drm_connector_state *state)
  {
  	memcpy(state, connector->state, sizeof(*state));
  }
  EXPORT_SYMBOL(__drm_atomic_helper_connector_duplicate_state);
  
  /**
   * drm_atomic_helper_connector_duplicate_state - default state duplicate hook
   * @connector: drm connector
   *
   * Default connector state duplicate hook for drivers which don't have their own
   * subclassed connector state structure.
   */
  struct drm_connector_state *
  drm_atomic_helper_connector_duplicate_state(struct drm_connector *connector)
  {
  	struct drm_connector_state *state;
  
  	if (WARN_ON(!connector->state))
  		return NULL;
  
  	state = kmalloc(sizeof(*state), GFP_KERNEL);
  	if (state)
  		__drm_atomic_helper_connector_duplicate_state(connector, state);
  
  	return state;
  }
  EXPORT_SYMBOL(drm_atomic_helper_connector_duplicate_state);
  
  /**
   * __drm_atomic_helper_connector_destroy_state - release connector state
   * @connector: connector object
   * @state: connector state object to release
   *
   * Releases all resources stored in the connector state without actually
   * freeing the memory of the connector state. This is useful for drivers that
   * subclass the connector state.
   */
  void
  __drm_atomic_helper_connector_destroy_state(struct drm_connector *connector,
  					    struct drm_connector_state *state)
  {
  	/*
  	 * This is currently a placeholder so that drivers that subclass the
  	 * state will automatically do the right thing if code is ever added
  	 * to this function.
  	 */
  }
  EXPORT_SYMBOL(__drm_atomic_helper_connector_destroy_state);
  
  /**
   * drm_atomic_helper_connector_destroy_state - default state destroy hook
   * @connector: drm connector
   * @state: connector state object to release
   *
   * Default connector state destroy hook for drivers which don't have their own
   * subclassed connector state structure.
   */
  void drm_atomic_helper_connector_destroy_state(struct drm_connector *connector,
  					  struct drm_connector_state *state)
  {
  	__drm_atomic_helper_connector_destroy_state(connector, state);
  	kfree(state);
  }
  EXPORT_SYMBOL(drm_atomic_helper_connector_destroy_state);
  