Hi Daniel,
Thank you for the patch.
On Wednesday 08 Mar 2017 15:12:39 Daniel Vetter wrote:
> 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@xxxxxxxxxxxxxxxx>
> Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx>
Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> ---
> include/drm/drm_crtc.h | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> 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;
--
Regards,
Laurent Pinchart
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