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. Cc: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> Reviewed-by: Thierry Reding <treding@xxxxxxxxxx> (v1 on irc) Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx> --- drivers/gpu/drm/drm_atomic_helper.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c index 12c25c54309f..bd23b4dc7f43 100644 --- a/drivers/gpu/drm/drm_atomic_helper.c +++ b/drivers/gpu/drm/drm_atomic_helper.c @@ -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 +1184,12 @@ 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. + * + * Note that for drivers supporting runtime PM, or which are otherwise unhappy if + * their plane update hooks get called on CRTCs which are off, it is highly + * recommended to set @active_only to true. Setting @active_only to false as the + * default implementation in drm_atomic_helper_commit() does is just done to + * most closely match the behaviour of the legacy helpers. */ void drm_atomic_helper_commit_planes(struct drm_device *dev, struct drm_atomic_state *old_state, -- 2.5.1 _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
