drm: atomic: Clarify documentation around drm_atomic_crtc_needs_modeset

Add some additional comments to more explicitly describe the meaning and
usage of the three CRTC modeset detection booleans: mode_changed,
connectors_changed and active_changed.

Suggested-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Brian Starkey <brian.starkey@arm.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1476352028-16701-1-git-send-email-brian.starkey@arm.com
This commit is contained in:
Brian Starkey
2016-10-13 10:47:08 +01:00
committed by Daniel Vetter
parent f7741aa75e
commit d807ed1c55
3 changed files with 20 additions and 5 deletions

View File

@@ -365,8 +365,17 @@ int __must_check drm_atomic_nonblocking_commit(struct drm_atomic_state *state);
*
* To give drivers flexibility struct &drm_crtc_state has 3 booleans to track
* whether the state CRTC changed enough to need a full modeset cycle:
* connectors_changed, mode_changed and active_change. This helper simply
* connectors_changed, mode_changed and active_changed. This helper simply
* combines these three to compute the overall need for a modeset for @state.
*
* The atomic helper code sets these booleans, but drivers can and should
* change them appropriately to accurately represent whether a modeset is
* really needed. In general, drivers should avoid full modesets whenever
* possible.
*
* For example if the CRTC mode has changed, and the hardware is able to enact
* the requested mode change without going through a full modeset, the driver
* should clear mode_changed during its ->atomic_check.
*/
static inline bool
drm_atomic_crtc_needs_modeset(struct drm_crtc_state *state)