drm: Global atomic state handling

Some differences compared to Rob's patches again:
- Dropped the committed and checked booleans. Checking will be
internally enforced by always calling ->atomic_check before
->atomic_commit. And async handling needs to be solved differently
because the current scheme completely side-steps ww mutex deadlock
avoidance (and so either reinvents a new deadlock avoidance wheel or
like the current code just deadlocks).

- State for connectors needed to be added, since now they have a
full-blown drm_connector_state (so that drivers have something to
attach their own stuff to).

- Refcounting is gone. I plane to solve async updates differently,
since the lock-passing scheme doesn't cut it (since it abuses ww
mutexes). Essentially what we need for async is a simple ownership
transfer from the caller to the driver. That doesn't need full-blown
refcounting.

- The acquire ctx is a pointer. Real atomic callers should have that
on their stack, legacy entry points need to put the right one
(obtained by drm_modeset_legacy_acuire_ctx) in there.

- I've dropped all hooks except check/commit. All the begin/end
handling is done by core functions and is the same.

- commit/check are just thin wrappers that ensure that ->check is
always called.

- To help out with locking in the legacy implementations I've added a
helper to just grab all locks in the backoff case.

v2: Add notices that check/commit can fail with EDEADLK.

v3:
- More consistent naming for state_alloc.
- Add state_clear which is needed for backoff and retry.

v4: Planes/connectors can switch between crtcs, and we need to be
careful that we grab the state (and locks) for both the old and new
crtc. Improve the interface functions to ensure this.

v5: Add functions to grab affected connectors for a crtc and to recompute
the crtc->enable state. This is useful for both helper and atomic ioctl
code when e.g. removing a connector.

v6: Squash in fixup from Fengguang to use ERR_CAST.

v7: Add debug output.

v8: Make checkpatch happy about kcalloc argument ordering.

v9: Improve kerneldoc in drm_crtc.h

v10:
- Fix another kcalloc argument misorder I've missed.
- More polish for kerneldoc.

v11: Clarify the ownership rules for the state object. The new rule is
that a successful drm_atomic_commit (whether synchronous or asnyc)
always inherits the state and is responsible for the clean-up. That
way async and sync ->commit functions are more similar.

v12: A few bugfixes:
- Assign state->state pointers correctly when grabbing state objects -
we need to link them up with the global state.
- Handle a NULL crtc in set_crtc_for_plane to simplify code flow a bit
for the callers of this function.

v13: Review from Sean:
- kerneldoc spelling fixes
- Don't overallocate states->planes.
- Handle NULL crtc in set_crtc_for_connector.

v14: Sprinkle __must_check over all functions which do wait/wound
locking to make sure callers don't forget this. Since I have ;-)

v15: Be more explicit in the kerneldoc when functions can return
-EDEADLK what to do. And that every other -errno is fatal.

v16: Indent with tabs instead of space, spotted by Ander.

v17: Review from Thierry, small kerneldoc and other naming polish.

Cc: Thierry Reding <[e-mail]>
Cc: Ander Conselvan de Oliveira <[e-mail]>
Cc: Daniel Thompson <[e-mail]>
Cc: Fengguang Wu <[e-mail]>
Cc: Sean Paul <[e-mail]>
Cc: Matt Roper <[e-mail]>
Reviewed-by: Sean Paul <[e-mail]>
Signed-off-by: Daniel Vetter <[e-mail]>

Documentation/DocBook/drm.tmpl

···
 !Edrivers/gpu/drm/drm_modes.c
     </sect2>
     <sect2>
+      <title>Atomic Mode Setting Function Reference</title>
+!Edrivers/gpu/drm/drm_atomic.c
+    </sect2>
+    <sect2>
       <title>Frame Buffer Creation</title>
       <synopsis>struct drm_framebuffer *(*fb_create)(struct drm_device *dev,
 				     struct drm_file *file_priv,

drivers/gpu/drm/Makefile

···
 		drm_info.o drm_debugfs.o drm_encoder_slave.o \
 		drm_trace_points.o drm_global.o drm_prime.o \
 		drm_rect.o drm_vma_manager.o drm_flip_work.o \
-		drm_modeset_lock.o
+		drm_modeset_lock.o drm_atomic.o
 
 drm-$(CONFIG_COMPAT) += drm_ioc32.o
 drm-$(CONFIG_DRM_GEM_CMA_HELPER) += drm_gem_cma_helper.o

drivers/gpu/drm/drm_atomic.c

···
+/*
+ * 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 <[e-mail]>
+ * Daniel Vetter <[e-mail]>
+ */
+
+
+#include <drm/drmP.h>
+#include <drm/drm_atomic.h>
+#include <drm/drm_plane_helper.h>
+
+static void kfree_state(struct drm_atomic_state *state)
+{
+	kfree(state->connectors);
+	kfree(state->connector_states);
+	kfree(state->crtcs);
+	kfree(state->crtc_states);
+	kfree(state->planes);
+	kfree(state->plane_states);
+	kfree(state);
+}
+
+/**
+ * drm_atomic_state_alloc - allocate atomic state
+ * @dev: DRM device
+ *
+ * This allocates an empty atomic state to track updates.
+ */
+struct drm_atomic_state *
+drm_atomic_state_alloc(struct drm_device *dev)
+{
+	struct drm_atomic_state *state;
+
+	state = kzalloc(sizeof(*state), GFP_KERNEL);
+	if (!state)
+		return NULL;
+
+	state->crtcs = kcalloc(dev->mode_config.num_crtc,
+			       sizeof(*state->crtcs), GFP_KERNEL);
+	if (!state->crtcs)
+		goto fail;
+	state->crtc_states = kcalloc(dev->mode_config.num_crtc,
+				     sizeof(*state->crtc_states), GFP_KERNEL);
+	if (!state->crtc_states)
+		goto fail;
+	state->planes = kcalloc(dev->mode_config.num_total_plane,
+				sizeof(*state->planes), GFP_KERNEL);
+	if (!state->planes)
+		goto fail;
+	state->plane_states = kcalloc(dev->mode_config.num_total_plane,
+				      sizeof(*state->plane_states), GFP_KERNEL);
+	if (!state->plane_states)
+		goto fail;
+	state->connectors = kcalloc(dev->mode_config.num_connector,
+				    sizeof(*state->connectors),
+				    GFP_KERNEL);
+	if (!state->connectors)
+		goto fail;
+	state->connector_states = kcalloc(dev->mode_config.num_connector,
+					  sizeof(*state->connector_states),
+					  GFP_KERNEL);
+	if (!state->connector_states)
+		goto fail;
+
+	state->dev = dev;
+
+	DRM_DEBUG_KMS("Allocate atomic state %p\n", state);
+
+	return state;
+fail:
+	kfree_state(state);
+
+	return NULL;
+}
+EXPORT_SYMBOL(drm_atomic_state_alloc);
+
+/**
+ * drm_atomic_state_clear - clear state object
+ * @state: atomic state
+ *
+ * When the w/w mutex algorithm detects a deadlock we need to back off and drop
+ * all locks. So someone else could sneak in and change the current modeset
+ * configuration. Which means that all the state assembled in @state is no
+ * longer an atomic update to the current state, but to some arbitrary earlier
+ * state. Which could break assumptions the driver's ->atomic_check likely
+ * relies on.
+ *
+ * Hence we must clear all cached state and completely start over, using this
+ * function.
+ */
+void drm_atomic_state_clear(struct drm_atomic_state *state)
+{
+	struct drm_device *dev = state->dev;
+	int i;
+
+	DRM_DEBUG_KMS("Clearing atomic state %p\n", state);
+
+	for (i = 0; i < dev->mode_config.num_connector; i++) {
+		struct drm_connector *connector = state->connectors[i];
+
+		if (!connector)
+			continue;
+
+		connector->funcs->atomic_destroy_state(connector,
+						       state->connector_states[i]);
+	}
+
+	for (i = 0; i < dev->mode_config.num_crtc; i++) {
+		struct drm_crtc *crtc = state->crtcs[i];
+
+		if (!crtc)
+			continue;
+
+		crtc->funcs->atomic_destroy_state(crtc,
+						  state->crtc_states[i]);
+	}
+
+	for (i = 0; i < dev->mode_config.num_total_plane; i++) {
+		struct drm_plane *plane = state->planes[i];
+
+		if (!plane)
+			continue;
+
+		plane->funcs->atomic_destroy_state(plane,
+						   state->plane_states[i]);
+	}
+}
+EXPORT_SYMBOL(drm_atomic_state_clear);
+
+/**
+ * drm_atomic_state_free - free all memory for an atomic state
+ * @state: atomic state to deallocate
+ *
+ * This frees all memory associated with an atomic state, including all the
+ * per-object state for planes, crtcs and connectors.
+ */
+void drm_atomic_state_free(struct drm_atomic_state *state)
+{
+	drm_atomic_state_clear(state);
+
+	DRM_DEBUG_KMS("Freeing atomic state %p\n", state);
+
+	kfree_state(state);
+}
+EXPORT_SYMBOL(drm_atomic_state_free);
+
+/**
+ * drm_atomic_get_crtc_state - get crtc state
+ * @state: global atomic state object
+ * @crtc: crtc to get state object for
+ *
+ * This function returns the crtc state for the given crtc, allocating it if
+ * needed. It will also grab the relevant crtc lock to make sure that the state
+ * is consistent.
+ *
+ * Returns:
+ *
+ * Either the allocated state or the error code encoded into the pointer. When
+ * the error is EDEADLK then the w/w mutex code has detected a deadlock and the
+ * entire atomic sequence must be restarted. All other errors are fatal.
+ */
+struct drm_crtc_state *
+drm_atomic_get_crtc_state(struct drm_atomic_state *state,
+			  struct drm_crtc *crtc)
+{
+	int ret, index;
+	struct drm_crtc_state *crtc_state;
+
+	index = drm_crtc_index(crtc);
+
+	if (state->crtc_states[index])
+		return state->crtc_states[index];
+
+	ret = drm_modeset_lock(&crtc->mutex, state->acquire_ctx);
+	if (ret)
+		return ERR_PTR(ret);
+
+	crtc_state = crtc->funcs->atomic_duplicate_state(crtc);
+	if (!crtc_state)
+		return ERR_PTR(-ENOMEM);
+
+	state->crtc_states[index] = crtc_state;
+	state->crtcs[index] = crtc;
+	crtc_state->state = state;
+
+	DRM_DEBUG_KMS("Added [CRTC:%d] %p state to %p\n",
+		      crtc->base.id, crtc_state, state);
+
+	return crtc_state;
+}
+EXPORT_SYMBOL(drm_atomic_get_crtc_state);
+
+/**
+ * drm_atomic_get_plane_state - get plane state
+ * @state: global atomic state object
+ * @plane: plane to get state object for
+ *
+ * This function returns the plane state for the given plane, allocating it if
+ * needed. It will also grab the relevant plane lock to make sure that the state
+ * is consistent.
+ *
+ * Returns:
+ *
+ * Either the allocated state or the error code encoded into the pointer. When
+ * the error is EDEADLK then the w/w mutex code has detected a deadlock and the
+ * entire atomic sequence must be restarted. All other errors are fatal.
+ */
+struct drm_plane_state *
+drm_atomic_get_plane_state(struct drm_atomic_state *state,
+			  struct drm_plane *plane)
+{
+	int ret, index;
+	struct drm_plane_state *plane_state;
+
+	index = drm_plane_index(plane);
+
+	if (state->plane_states[index])
+		return state->plane_states[index];
+
+	/*
+	 * TODO: We currently don't have per-plane mutexes. So instead of trying
+	 * crazy tricks with deferring plane->crtc and hoping for the best just
+	 * grab all crtc locks. Once we have per-plane locks we must update this
+	 * to only take the plane mutex.
+	 */
+	ret = drm_modeset_lock_all_crtcs(state->dev, state->acquire_ctx);
+	if (ret)
+		return ERR_PTR(ret);
+
+	plane_state = plane->funcs->atomic_duplicate_state(plane);
+	if (!plane_state)
+		return ERR_PTR(-ENOMEM);
+
+	state->plane_states[index] = plane_state;
+	state->planes[index] = plane;
+	plane_state->state = state;
+
+	DRM_DEBUG_KMS("Added [PLANE:%d] %p state to %p\n",
+		      plane->base.id, plane_state, state);
+
+	if (plane_state->crtc) {
+		struct drm_crtc_state *crtc_state;
+
+		crtc_state = drm_atomic_get_crtc_state(state,
+						       plane_state->crtc);
+		if (IS_ERR(crtc_state))
+			return ERR_CAST(crtc_state);
+	}
+
+	return plane_state;
+}
+EXPORT_SYMBOL(drm_atomic_get_plane_state);
+
+/**
+ * drm_atomic_get_connector_state - get connector state
+ * @state: global atomic state object
+ * @connector: connector to get state object for
+ *
+ * This function returns the connector state for the given connector,
+ * allocating it if needed. It will also grab the relevant connector lock to
+ * make sure that the state is consistent.
+ *
+ * Returns:
+ *
+ * Either the allocated state or the error code encoded into the pointer. When
+ * the error is EDEADLK then the w/w mutex code has detected a deadlock and the
+ * entire atomic sequence must be restarted. All other errors are fatal.
+ */
+struct drm_connector_state *
+drm_atomic_get_connector_state(struct drm_atomic_state *state,
+			  struct drm_connector *connector)
+{
+	int ret, index;
+	struct drm_mode_config *config = &connector->dev->mode_config;
+	struct drm_connector_state *connector_state;
+
+	index = drm_connector_index(connector);
+
+	if (state->connector_states[index])
+		return state->connector_states[index];
+
+	ret = drm_modeset_lock(&config->connection_mutex, state->acquire_ctx);
+	if (ret)
+		return ERR_PTR(ret);
+
+	connector_state = connector->funcs->atomic_duplicate_state(connector);
+	if (!connector_state)
+		return ERR_PTR(-ENOMEM);
+
+	state->connector_states[index] = connector_state;
+	state->connectors[index] = connector;
+	connector_state->state = state;
+
+	DRM_DEBUG_KMS("Added [CONNECTOR:%d] %p state to %p\n",
+		      connector->base.id, connector_state, state);
+
+	if (connector_state->crtc) {
+		struct drm_crtc_state *crtc_state;
+
+		crtc_state = drm_atomic_get_crtc_state(state,
+						       connector_state->crtc);
+		if (IS_ERR(crtc_state))
+			return ERR_CAST(crtc_state);
+	}
+
+	return connector_state;
+}
+EXPORT_SYMBOL(drm_atomic_get_connector_state);
+
+/**
+ * drm_atomic_set_crtc_for_plane - set crtc for plane
+ * @plane_state: atomic state object for the plane
+ * @crtc: crtc to use for the plane
+ *
+ * Changing the assigned crtc for a plane requires us to grab the lock and state
+ * for the new crtc, as needed. This function takes care of all these details
+ * besides updating the pointer in the state object itself.
+ *
+ * Returns:
+ * 0 on success or can fail with -EDEADLK or -ENOMEM. When the error is EDEADLK
+ * then the w/w mutex code has detected a deadlock and the entire atomic
+ * sequence must be restarted. All other errors are fatal.
+ */
+int
+drm_atomic_set_crtc_for_plane(struct drm_plane_state *plane_state,
+			      struct drm_crtc *crtc)
+{
+	struct drm_crtc_state *crtc_state;
+
+	if (crtc) {
+		crtc_state = drm_atomic_get_crtc_state(plane_state->state,
+						       crtc);
+		if (IS_ERR(crtc_state))
+			return PTR_ERR(crtc_state);
+	}
+
+	plane_state->crtc = crtc;
+
+	if (crtc)
+		DRM_DEBUG_KMS("Link plane state %p to [CRTC:%d]\n",
+			      plane_state, crtc->base.id);
+	else
+		DRM_DEBUG_KMS("Link plane state %p to [NOCRTC]\n", plane_state);
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_atomic_set_crtc_for_plane);
+
+/**
+ * drm_atomic_set_crtc_for_connector - set crtc for connector
+ * @conn_state: atomic state object for the connector
+ * @crtc: crtc to use for the connector
+ *
+ * Changing the assigned crtc for a connector requires us to grab the lock and
+ * state for the new crtc, as needed. This function takes care of all these
+ * details besides updating the pointer in the state object itself.
+ *
+ * Returns:
+ * 0 on success or can fail with -EDEADLK or -ENOMEM. When the error is EDEADLK
+ * then the w/w mutex code has detected a deadlock and the entire atomic
+ * sequence must be restarted. All other errors are fatal.
+ */
+int
+drm_atomic_set_crtc_for_connector(struct drm_connector_state *conn_state,
+				  struct drm_crtc *crtc)
+{
+	struct drm_crtc_state *crtc_state;
+
+	if (crtc) {
+		crtc_state = drm_atomic_get_crtc_state(conn_state->state, crtc);
+		if (IS_ERR(crtc_state))
+			return PTR_ERR(crtc_state);
+	}
+
+	conn_state->crtc = crtc;
+
+	if (crtc)
+		DRM_DEBUG_KMS("Link connector state %p to [CRTC:%d]\n",
+			      conn_state, crtc->base.id);
+	else
+		DRM_DEBUG_KMS("Link connector state %p to [NOCRTC]\n",
+			      conn_state);
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_atomic_set_crtc_for_connector);
+
+/**
+ * drm_atomic_add_affected_connectors - add connectors for crtc
+ * @state: atomic state
+ * @crtc: DRM crtc
+ *
+ * This function walks the current configuration and adds all connectors
+ * currently using @crtc to the atomic configuration @state. Note that this
+ * function must acquire the connection mutex. This can potentially cause
+ * unneeded seralization if the update is just for the planes on one crtc. Hence
+ * drivers and helpers should only call this when really needed (e.g. when a
+ * full modeset needs to happen due to some change).
+ *
+ * Returns:
+ * 0 on success or can fail with -EDEADLK or -ENOMEM. When the error is EDEADLK
+ * then the w/w mutex code has detected a deadlock and the entire atomic
+ * sequence must be restarted. All other errors are fatal.
+ */
+int
+drm_atomic_add_affected_connectors(struct drm_atomic_state *state,
+				   struct drm_crtc *crtc)
+{
+	struct drm_mode_config *config = &state->dev->mode_config;
+	struct drm_connector *connector;
+	struct drm_connector_state *conn_state;
+	int ret;
+
+	ret = drm_modeset_lock(&config->connection_mutex, state->acquire_ctx);
+	if (ret)
+		return ret;
+
+	DRM_DEBUG_KMS("Adding all current connectors for [CRTC:%d] to %p\n",
+		      crtc->base.id, state);
+
+	/*
+	 * Changed connectors are already in @state, so only need to look at the
+	 * current configuration.
+	 */
+	list_for_each_entry(connector, &config->connector_list, head) {
+		if (connector->state->crtc != crtc)
+			continue;
+
+		conn_state = drm_atomic_get_connector_state(state, connector);
+		if (IS_ERR(conn_state))
+			return PTR_ERR(conn_state);
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_atomic_add_affected_connectors);
+
+/**
+ * drm_atomic_connectors_for_crtc - count number of connected outputs
+ * @state: atomic state
+ * @crtc: DRM crtc
+ *
+ * This function counts all connectors which will be connected to @crtc
+ * according to @state. Useful to recompute the enable state for @crtc.
+ */
+int
+drm_atomic_connectors_for_crtc(struct drm_atomic_state *state,
+			       struct drm_crtc *crtc)
+{
+	int nconnectors = state->dev->mode_config.num_connector;
+	int i, num_connected_connectors = 0;
+
+	for (i = 0; i < nconnectors; i++) {
+		struct drm_connector_state *conn_state;
+
+		conn_state = state->connector_states[i];
+
+		if (conn_state && conn_state->crtc == crtc)
+			num_connected_connectors++;
+	}
+
+	DRM_DEBUG_KMS("State %p has %i connectors for [CRTC:%d]\n",
+		      state, num_connected_connectors, crtc->base.id);
+
+	return num_connected_connectors;
+}
+EXPORT_SYMBOL(drm_atomic_connectors_for_crtc);
+
+/**
+ * drm_atomic_legacy_backoff - locking backoff for legacy ioctls
+ * @state: atomic state
+ *
+ * This function should be used by legacy entry points which don't understand
+ * -EDEADLK semantics. For simplicity this one will grab all modeset locks after
+ *  the slowpath completed.
+ */
+void drm_atomic_legacy_backoff(struct drm_atomic_state *state)
+{
+	int ret;
+
+retry:
+	drm_modeset_backoff(state->acquire_ctx);
+
+	ret = drm_modeset_lock(&state->dev->mode_config.connection_mutex,
+			       state->acquire_ctx);
+	if (ret)
+		goto retry;
+	ret = drm_modeset_lock_all_crtcs(state->dev,
+					 state->acquire_ctx);
+	if (ret)
+		goto retry;
+}
+EXPORT_SYMBOL(drm_atomic_legacy_backoff);
+
+/**
+ * drm_atomic_check_only - check whether a given config would work
+ * @state: atomic configuration to check
+ *
+ * Note that this function can return -EDEADLK if the driver needed to acquire
+ * more locks but encountered a deadlock. The caller must then do the usual w/w
+ * backoff dance and restart. All other errors are fatal.
+ *
+ * Returns:
+ * 0 on success, negative error code on failure.
+ */
+int drm_atomic_check_only(struct drm_atomic_state *state)
+{
+	struct drm_mode_config *config = &state->dev->mode_config;
+
+	DRM_DEBUG_KMS("checking %p\n", state);
+
+	if (config->funcs->atomic_check)
+		return config->funcs->atomic_check(state->dev, state);
+	else
+		return 0;
+}
+EXPORT_SYMBOL(drm_atomic_check_only);
+
+/**
+ * drm_atomic_commit - commit configuration atomically
+ * @state: atomic configuration to check
+ *
+ * Note that this function can return -EDEADLK if the driver needed to acquire
+ * more locks but encountered a deadlock. The caller must then do the usual w/w
+ * backoff dance and restart. All other errors are fatal.
+ *
+ * Also note that on successful execution ownership of @state is transferred
+ * from the caller of this function to the function itself. The caller must not
+ * free or in any other way access @state. If the function fails then the caller
+ * must clean up @state itself.
+ *
+ * Returns:
+ * 0 on success, negative error code on failure.
+ */
+int drm_atomic_commit(struct drm_atomic_state *state)
+{
+	struct drm_mode_config *config = &state->dev->mode_config;
+	int ret;
+
+	ret = drm_atomic_check_only(state);
+	if (ret)
+		return ret;
+
+	DRM_DEBUG_KMS("commiting %p\n", state);
+
+	return config->funcs->atomic_commit(state->dev, state, false);
+}
+EXPORT_SYMBOL(drm_atomic_commit);
+
+/**
+ * drm_atomic_async_commit - atomic&async configuration commit
+ * @state: atomic configuration to check
+ *
+ * Note that this function can return -EDEADLK if the driver needed to acquire
+ * more locks but encountered a deadlock. The caller must then do the usual w/w
+ * backoff dance and restart. All other errors are fatal.
+ *
+ * Also note that on successful execution ownership of @state is transferred
+ * from the caller of this function to the function itself. The caller must not
+ * free or in any other way access @state. If the function fails then the caller
+ * must clean up @state itself.
+ *
+ * Returns:
+ * 0 on success, negative error code on failure.
+ */
+int drm_atomic_async_commit(struct drm_atomic_state *state)
+{
+	struct drm_mode_config *config = &state->dev->mode_config;
+	int ret;
+
+	ret = drm_atomic_check_only(state);
+	if (ret)
+		return ret;
+
+	DRM_DEBUG_KMS("commiting %p asynchronously\n", state);
+
+	return config->funcs->atomic_commit(state->dev, state, true);
+}
+EXPORT_SYMBOL(drm_atomic_async_commit);

include/drm/drm_atomic.h

···
+/*
+ * 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 <[e-mail]>
+ * Daniel Vetter <[e-mail]>
+ */
+
+#ifndef DRM_ATOMIC_H_
+#define DRM_ATOMIC_H_
+
+struct drm_atomic_state * __must_check
+drm_atomic_state_alloc(struct drm_device *dev);
+void drm_atomic_state_clear(struct drm_atomic_state *state);
+void drm_atomic_state_free(struct drm_atomic_state *state);
+
+struct drm_crtc_state * __must_check
+drm_atomic_get_crtc_state(struct drm_atomic_state *state,
+			  struct drm_crtc *crtc);
+struct drm_plane_state * __must_check
+drm_atomic_get_plane_state(struct drm_atomic_state *state,
+			   struct drm_plane *plane);
+struct drm_connector_state * __must_check
+drm_atomic_get_connector_state(struct drm_atomic_state *state,
+			       struct drm_connector *connector);
+
+int __must_check
+drm_atomic_set_crtc_for_plane(struct drm_plane_state *plane_state,
+			      struct drm_crtc *crtc);
+int __must_check
+drm_atomic_set_crtc_for_connector(struct drm_connector_state *conn_state,
+				  struct drm_crtc *crtc);
+int __must_check
+drm_atomic_add_affected_connectors(struct drm_atomic_state *state,
+				   struct drm_crtc *crtc);
+int
+drm_atomic_connectors_for_crtc(struct drm_atomic_state *state,
+			       struct drm_crtc *crtc);
+
+void drm_atomic_legacy_backoff(struct drm_atomic_state *state);
+
+int __must_check drm_atomic_check_only(struct drm_atomic_state *state);
+int __must_check drm_atomic_commit(struct drm_atomic_state *state);
+int __must_check drm_atomic_async_commit(struct drm_atomic_state *state);
+
+#endif /* DRM_ATOMIC_H_ */

include/drm/drm_crtc.h

···
 struct drm_atomic_state;
 
 /**
- * struct drm_crtc_state - mutable crtc state
+ * struct drm_crtc_state - mutable CRTC state
  * @enable: whether the CRTC should be enabled, gates all other state
  * @mode: current mode timings
  * @event: optional pointer to a DRM event to signal upon completion of the
···
  * @state: backpointer to global drm_atomic_state
  */
 struct drm_crtc_state {
-	bool enable        : 1;
+	bool enable;
 
 	struct drm_display_mode mode;
 
···
 	/* atomic update handling */
 	struct drm_crtc_state *(*atomic_duplicate_state)(struct drm_crtc *crtc);
 	void (*atomic_destroy_state)(struct drm_crtc *crtc,
-				     struct drm_crtc_state *cstate);
+				     struct drm_crtc_state *state);
 	int (*atomic_set_property)(struct drm_crtc *crtc,
 				   struct drm_crtc_state *state,
 				   struct drm_property *property,
···
 
 /**
  * struct drm_connector_state - mutable connector state
- * @crtc: crtc to connect connector to, NULL if disabled
+ * @crtc: CRTC to connect connector to, NULL if disabled
  * @state: backpointer to global drm_atomic_state
  */
 struct drm_connector_state {
···
  * @atomic_duplicate_state: duplicate the atomic state for this connector
  * @atomic_destroy_state: destroy an atomic state for this connector
  * @atomic_set_property: set a property on an atomic state for this connector
- *
  *
  * Each CRTC may have one or more connectors attached to it.  The functions
  * below allow the core DRM code to control connectors, enumerate available modes,
···
 	/* atomic update handling */
 	struct drm_connector_state *(*atomic_duplicate_state)(struct drm_connector *connector);
 	void (*atomic_destroy_state)(struct drm_connector *connector,
-				     struct drm_connector_state *cstate);
+				     struct drm_connector_state *state);
 	int (*atomic_set_property)(struct drm_connector *connector,
 				   struct drm_connector_state *state,
 				   struct drm_property *property,
···
 /**
  * struct drm_plane_state - mutable plane state
  * @crtc: currently bound CRTC, NULL if disabled
- * @fb: currently bound fb
+ * @fb: currently bound framebuffer
  * @crtc_x: left position of visible portion of plane on crtc
  * @crtc_y: upper position of visible portion of plane on crtc
  * @crtc_w: width of visible portion of plane on crtc
···
 	/* atomic update handling */
 	struct drm_plane_state *(*atomic_duplicate_state)(struct drm_plane *plane);
 	void (*atomic_destroy_state)(struct drm_plane *plane,
-				     struct drm_plane_state *cstate);
+				     struct drm_plane_state *state);
 	int (*atomic_set_property)(struct drm_plane *plane,
 				   struct drm_plane_state *state,
 				   struct drm_property *property,
···
 };
 
 /**
+ * struct struct drm_atomic_state - the global state object for atomic updates
+ * @dev: parent DRM device
+ * @flags: state flags like async update
+ * @planes: pointer to array of plane pointers
+ * @plane_states: pointer to array of plane states pointers
+ * @crtcs: pointer to array of CRTC pointers
+ * @crtc_states: pointer to array of CRTC states pointers
+ * @connectors: pointer to array of connector pointers
+ * @connector_states: pointer to array of connector states pointers
+ * @acquire_ctx: acquire context for this atomic modeset state update
+ */
+struct drm_atomic_state {
+	struct drm_device *dev;
+	uint32_t flags;
+	struct drm_plane **planes;
+	struct drm_plane_state **plane_states;
+	struct drm_crtc **crtcs;
+	struct drm_crtc_state **crtc_states;
+	struct drm_connector **connectors;
+	struct drm_connector_state **connector_states;
+
+	struct drm_modeset_acquire_ctx *acquire_ctx;
+};
+
+
+/**
  * struct drm_mode_set - new values for a CRTC config change
  * @fb: framebuffer to use for new config
  * @crtc: CRTC whose configuration we're about to change
···
  * struct drm_mode_config_funcs - basic driver provided mode setting functions
  * @fb_create: create a new framebuffer object
  * @output_poll_changed: function to handle output configuration changes
+ * @atomic_check: check whether a give atomic state update is possible
+ * @atomic_commit: commit an atomic state update previously verified with
+ * 	atomic_check()
  *
  * Some global (i.e. not per-CRTC, connector, etc) mode setting functions that
  * involve drivers.
···
 					     struct drm_file *file_priv,
 					     struct drm_mode_fb_cmd2 *mode_cmd);
 	void (*output_poll_changed)(struct drm_device *dev);
+
+	int (*atomic_check)(struct drm_device *dev,
+			    struct drm_atomic_state *a);
+	int (*atomic_commit)(struct drm_device *dev,
+			     struct drm_atomic_state *a,
+			     bool async);
 };
 
 /**