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author | Daniel Vetter <daniel.vetter@ffwll.ch> | 2017-03-08 15:12:39 +0100 |
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committer | Daniel Vetter <daniel.vetter@ffwll.ch> | 2017-03-09 16:18:02 +0100 |
commit | 66f8c10003966130b0b2812fcbdfa6389bccd577 (patch) | |
tree | 145c38d6f3974c18fcb84d704dcaf9f95d9c338e /include/drm/drm_crtc.h | |
parent | drm: Remove drmP.h include from drm_kms_helper_common.c (diff) | |
download | linux-66f8c10003966130b0b2812fcbdfa6389bccd577.tar.xz linux-66f8c10003966130b0b2812fcbdfa6389bccd577.zip |
drm/doc: document fallback behaviour for atomic events
Worst case if the hw can't support completion signalling in a
race-free way we want the event to be too late, not too early.
Text adapted from a proposal from Laurent - the other side of how to
make hw work correctly where it's possible is imo already sufficiently
documented.
v2: Review from Laurent.
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170308141257.12119-7-daniel.vetter@ffwll.ch
Diffstat (limited to 'include/drm/drm_crtc.h')
-rw-r--r-- | include/drm/drm_crtc.h | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h index cba29ffedafd..6ef59da3fd8e 100644 --- a/include/drm/drm_crtc.h +++ b/include/drm/drm_crtc.h @@ -204,6 +204,12 @@ struct drm_crtc_state { * drm_crtc_arm_vblank_event(). See the documentation of that function * for a detailed discussion of the constraints it needs to be used * safely. + * + * If the device can't notify of flip completion in a race-free way + * at all, then the event should be armed just after the page flip is + * committed. In the worst case the driver will send the event to + * userspace one frame too late. This doesn't allow for a real atomic + * update, but it should avoid tearing. */ struct drm_pending_vblank_event *event; |