On Friday, January 17th, 2025 at 12:15, Pekka Paalanen
<pekka.paala...@haloniitty.fi> wrote:
> On Thu, 16 Jan 2025 16:25:35 +0000
> Simon Ser cont...@emersion.fr wrote:
>
> > It's not obvious off-hand which CRTCs will get a page-flip event
> > when using this flag in an atomic commit, because it's all
> > implicitly implied based on the contents of the atomic commit.
> > Document requirements for using this flag and
>
> and?
Oops, sounds like I stopped here to write the next paragraph and forgot
to go back and finish the sentence…
> > Note, because prepare_signaling() runs right after
> > drm_atomic_set_property() calls, page-flip events are not delivered
> > for CRTCs pulled in later by DRM core (e.g. on modeset by
> > drm_atomic_helper_check_modeset()) or the driver (e.g. other CRTCs
> > sharing a DP-MST connector).
> >
> > Signed-off-by: Simon Ser cont...@emersion.fr
> > Cc: Simona Vetter simona.vet...@ffwll.ch
> > Cc: Ville Syrjälä ville.syrj...@linux.intel.com
> > Cc: Pekka Paalanen pekka.paala...@collabora.com
> > Cc: David Turner david.tur...@raspberrypi.com
> > ---
> > include/uapi/drm/drm_mode.h | 8 ++++++++
> > 1 file changed, 8 insertions(+)
> >
> > diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
> > index c082810c08a8..a122bea25593 100644
> > --- a/include/uapi/drm/drm_mode.h
> > +++ b/include/uapi/drm/drm_mode.h
> > @@ -962,6 +962,14 @@ struct hdr_output_metadata {
> > * Request that the kernel sends back a vblank event (see
> > * struct drm_event_vblank) with the &DRM_EVENT_FLIP_COMPLETE type when the
> > * page-flip is done.
> > + *
> > + * When used with atomic uAPI, one event will be delivered per CRTC
> > included in
> > + * the atomic commit. A CRTC is included in an atomic commit if one of its
> > + * properties is set, or if a property is set on a connector or plane
> > linked
> > + * via the CRTC_ID property to the CRTC. At least one CRTC must be
> > included,
> > + * and all pulled in CRTCs must be either previously or newly powered on
> > (in
> > + * other words, a powered off CRTC which stays off cannot be included in
> > the
> > + * atomic commit).
>
> Sounds right. I imagine this doc needs to be extended when drm_colorop
> lands, as yet another way to pull in a CRTC.
Yeah, I suppose so.
> Wasn't this also conditional on the DRM_CAP_CRTC_IN_VBLANK_EVENT or did
> userspace really need to count the events even without it?
DRM_CAP_CRTC_IN_VBLANK_EVENT is unconditionally set to 1. It doesn't seem
like there is any interaction between these two. So yeah, I suppose
user-space needs to count if they are on kernel < v4.12.
> Nevertheless, should there be a "see also DRM_CAP_CRTC_IN_VBLANK_EVENT"?
This sounds a bit out-of-place to me TBH. It's orthogonal to event delivery
and it's linked from struct drm_event_vblank already.
