EXPORT_SYMBOL(drm_atomic_helper_wait_for_vblanks);
/**
- * drm_atomic_helper_commit - commit validated state object
- * @dev: DRM device
- * @state: the driver state object
- * @nonblocking: whether nonblocking behavior is requested.
+ * drm_atomic_helper_commit_tail - commit atomic update to hardware
+ * @state: new modeset state to be committed
*
- * 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 nonblocking commits.
+ * This is the default implemenation for the ->atomic_commit_tail() hook of the
+ * &drm_mode_config_helper_funcs vtable.
*
- * Note that right now this function does not support nonblocking commits, hence
- * driver writers must implement their own version for now. Also note that the
- * default ordering of how the various stages are called is to match the legacy
- * modeset helper library closest. One peculiarity of that is that it doesn't
- * mesh well with runtime PM at all.
+ * Note that the default ordering of how the various stages are called is to
+ * match the legacy modeset helper library closest. One peculiarity of that is
+ * that it doesn't mesh well with runtime PM at all.
*
- * For drivers supporting runtime PM the recommended sequence is
+ * For drivers supporting runtime PM the recommended sequence is instead ::
*
* drm_atomic_helper_commit_modeset_disables(dev, state);
*
*
* drm_atomic_helper_commit_planes(dev, state, true);
*
- * See the kerneldoc entries for these three functions for more details.
+ * for committing the atomic update to hardware. See the kerneldoc entries for
+ * these three functions for more details.
+ */
+void drm_atomic_helper_commit_tail(struct drm_atomic_state *state)
+{
+ struct drm_device *dev = state->dev;
+
+ drm_atomic_helper_commit_modeset_disables(dev, state);
+
+ drm_atomic_helper_commit_planes(dev, state, false);
+
+ drm_atomic_helper_commit_modeset_enables(dev, state);
+
+ drm_atomic_helper_commit_hw_done(state);
+
+ drm_atomic_helper_wait_for_vblanks(dev, state);
+
+ drm_atomic_helper_cleanup_planes(dev, state);
+}
+EXPORT_SYMBOL(drm_atomic_helper_commit_tail);
+
+static void commit_tail(struct drm_atomic_state *state)
+{
+ struct drm_device *dev = state->dev;
+ struct drm_mode_config_helper_funcs *funcs;
+
+ funcs = dev->mode_config.helper_private;
+
+ drm_atomic_helper_wait_for_fences(dev, state);
+
+ drm_atomic_helper_wait_for_dependencies(state);
+
+ if (funcs && funcs->atomic_commit_tail)
+ funcs->atomic_commit_tail(state);
+ else
+ drm_atomic_helper_commit_tail(state);
+
+ drm_atomic_helper_commit_cleanup_done(state);
+
+ drm_atomic_state_free(state);
+}
+
+static void commit_work(struct work_struct *work)
+{
+ struct drm_atomic_state *state = container_of(work,
+ struct drm_atomic_state,
+ commit_work);
+ commit_tail(state);
+}
+
+/**
+ * drm_atomic_helper_commit - commit validated state object
+ * @dev: DRM device
+ * @state: the driver state object
+ * @nonblock: whether nonblocking behavior is requested.
+ *
+ * This function commits a with drm_atomic_helper_check() pre-validated state
+ * object. This can still fail when e.g. the framebuffer reservation fails. This
+ * function implements nonblocking commits, using
+ * drm_atomic_helper_setup_commit() and related functions.
+ *
+ * Note that right now this function does not support nonblocking commits, hence
+ * driver writers must implement their own version for now.
+ *
+ * Committing the actual hardware state is done through the
+ * ->atomic_commit_tail() callback of the &drm_mode_config_helper_funcs vtable,
+ * or it's default implementation drm_atomic_helper_commit_tail().
*
* RETURNS:
* Zero for success or -errno.
{
int ret;
- if (nonblock)
- return -EBUSY;
-
ret = drm_atomic_helper_setup_commit(state, nonblock);
if (ret)
return ret;
+ INIT_WORK(&state->commit_work, commit_work);
+
ret = drm_atomic_helper_prepare_planes(dev, state);
if (ret)
return ret;
* update. Which is important since compositors need to figure out the
* composition of the next frame right after having submitted the
* current layout.
+ *
+ * NOTE: Commit work has multiple phases, first hardware commit, then
+ * cleanup. We want them to overlap, hence need system_unbound_wq to
+ * make sure work items don't artifically stall on each another.
*/
- drm_atomic_helper_wait_for_fences(dev, state);
-
- drm_atomic_helper_wait_for_dependencies(state);
-
- drm_atomic_helper_commit_modeset_disables(dev, state);
-
- drm_atomic_helper_commit_planes(dev, state, false);
-
- drm_atomic_helper_commit_modeset_enables(dev, state);
-
- drm_atomic_helper_commit_hw_done(state);
-
- drm_atomic_helper_wait_for_vblanks(dev, state);
-
- drm_atomic_helper_cleanup_planes(dev, state);
-
- drm_atomic_helper_commit_cleanup_done(state);
-
- drm_atomic_state_free(state);
+ if (nonblock)
+ queue_work(system_unbound_wq, &state->commit_work);
+ else
+ commit_tail(state);
return 0;
}
/**
* DOC: implementing nonblocking commit
*
- * For now the atomic helpers don't support nonblocking 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 nonblocking commit themselves, with the
- * following sequence being the recommended one:
+ * Nonblocking atomic commits have to be implemented in the following sequence:
*
* 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
* 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.
+ * Asynchronous workers need to have sufficient parallelism to be able to run
+ * different atomic commits on different CRTCs in parallel. The simplest way to
+ * achive this is by running them on the &system_unbound_wq work queue. Note
+ * that drivers are not required to split up atomic commits and run an
+ * individual commit in parallel - userspace is supposed to do that if it cares.
+ * But it might be beneficial to do that for modesets, since those necessarily
+ * must be done as one global operation, and enabling or disabling a CRTC can
+ * take a long time. But even that is not required.
*
* 3. The software state is updated synchronously with
* drm_atomic_helper_swap_state(). Doing this under the protection of all modeset
* 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.
+ *
+ * The above scheme is implemented in the atomic helper libraries in
+ * drm_atomic_helper_commit() using a bunch of helper functions. See
+ * drm_atomic_helper_setup_commit() for a starting point.
*/
static int stall_checks(struct drm_crtc *crtc, bool nonblock)
projects / cascardo / linux.git / blobdiff