[RFC PATCH 3/4] drm/doc: document PAGE_FLIP_EVENT | PAGE_FLIP_ASYNC

[Pekka Paalanen]

On Wed, 12 Jul 2023 13:57:32 +0000
Simon Ser <contact at emersion.fr> wrote:

> Explain what the event looks like when both flags are specified.
> 
> Signed-off-by: Simon Ser <contact at emersion.fr>
> Cc: Pekka Paalanen <pekka.paalanen at collabora.com>
> Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Cc: Lyude Paul <lyude at redhat.com>
> Cc: Christian König <ckoenig.leichtzumerken at gmail.com>
> ---
> 
> Driver developers: please confirm or deny this documentation. I'm just
> guessing here.
> 
>  include/uapi/drm/drm_mode.h | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
> index c32b171c0ba7..cb4bbfe15d3a 100644
> --- a/include/uapi/drm/drm_mode.h
> +++ b/include/uapi/drm/drm_mode.h
> @@ -950,6 +950,9 @@ struct hdr_output_metadata {
>   * When used with the atomic uAPI, vblank events will be sent for every CRTC
>   * included in the commit. At least one CRTC must be included, and all included
>   * CRTCs must be turned on.
> + *
> + * When used with &DRM_MODE_PAGE_FLIP_ASYNC, the page-flip event will have the
> + * same timings and sequence number as the previous effective page-flip.
>   */
>  #define DRM_MODE_PAGE_FLIP_EVENT 0x01
>  /**

This wording would mean that if you do a continuous stream of async
flips indefinitely, the timestamp and sequence number would never
change at all. I think "the previous effective page-flip" needs
different words.

Hmm, no. I'm misunderstanding "effective" here. But all the flips are
effective, right? All will be programmed into hardware.


Thanks,
pq