diff options
Diffstat (limited to 'drivers/gpu')
| -rw-r--r-- | drivers/gpu/drm/drm_atomic_helper.c | 144 |
1 files changed, 98 insertions, 46 deletions
diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c index 6dee09cfbf93..6a13df8691d4 100644 --- a/drivers/gpu/drm/drm_atomic_helper.c +++ b/drivers/gpu/drm/drm_atomic_helper.c @@ -1120,22 +1120,17 @@ drm_atomic_helper_wait_for_vblanks(struct drm_device *dev, 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); * @@ -1143,7 +1138,73 @@ EXPORT_SYMBOL(drm_atomic_helper_wait_for_vblanks); * * 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. @@ -1154,13 +1215,12 @@ int drm_atomic_helper_commit(struct drm_device *dev, { 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; @@ -1187,27 +1247,16 @@ int drm_atomic_helper_commit(struct drm_device *dev, * 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; } @@ -1216,12 +1265,7 @@ EXPORT_SYMBOL(drm_atomic_helper_commit); /** * 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 @@ -1233,10 +1277,14 @@ EXPORT_SYMBOL(drm_atomic_helper_commit); * 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 @@ -1249,6 +1297,10 @@ EXPORT_SYMBOL(drm_atomic_helper_commit); * 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) |