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drm/atomic-helper: Pimp docs with recommendations for rpm drivers 

Requested by Laurent.

Note that this uses the new markdown support which will only land in
kernel 4.4 (for the code snippet).

v2: A few spelling fixes I spotted myself.

v3: Big reword for commit_planes() kerneldoc based on a text from
Laurent.

Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Thierry Reding <treding@nvidia.com> (v1 on irc)
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
hifive-unleashed-5.1
Daniel Vetter 2015-09-08 13:52:45 +02:00
parent aef9dbb8f7
commit 6e48ae3269
1 changed files with 32 additions and 0 deletions
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32
drivers/gpu/drm/drm_atomic_helper.c
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@ -993,6 +993,22 @@ EXPORT_SYMBOL(drm_atomic_helper_wait_for_vblanks);
* object. This can still fail when e.g. the framebuffer reservation fails. For
* now this doesn't implement asynchronous commits.
*
* Note that right now this function does not support async commits, and 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.
*
* For drivers supporting runtime PM the recommended sequence is
*
* drm_atomic_helper_commit_modeset_disables(dev, state);
*
* drm_atomic_helper_commit_modeset_enables(dev, state);
*
* drm_atomic_helper_commit_planes(dev, state, true);
*
* See the kerneldoc entries for these three functions for more details.
*
* RETURNS
* Zero for success or -errno.
*/
@ -1168,6 +1184,22 @@ bool plane_crtc_active(struct drm_plane_state *state)
* Note that this function does all plane updates across all CRTCs in one step.
* If the hardware can't support this approach look at
* drm_atomic_helper_commit_planes_on_crtc() instead.
*
* Plane parameters can be updated by applications while the associated CRTC is
* disabled. The DRM/KMS core will store the parameters in the plane state,
* which will be available to the driver when the CRTC is turned on. As a result
* most drivers don't need to be immediately notified of plane updates for a
* disabled CRTC.
*
* Unless otherwise needed, drivers are advised to set the @active_only
* parameters to true in order not to receive plane update notifications related
* to a disabled CRTC. This avoids the need to manually ignore plane updates in
* driver code when the driver and/or hardware can't or just don't need to deal
* with updates on disabled CRTCs, for example when supporting runtime PM.
*
* The drm_atomic_helper_commit() default implementation only sets @active_only
* to false to most closely match the behaviour of the legacy helpers. This should
* not be copied blindly by drivers.
*/
void drm_atomic_helper_commit_planes(struct drm_device *dev,
struct drm_atomic_state *old_state,