On Mon, 14 Apr 2025 at 09:24, Simon Ser <cont...@emersion.fr> wrote: > On Friday, January 17th, 2025 at 12:15, Pekka Paalanen > <pekka.paala...@haloniitty.fi> wrote: > > 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.
Right. One completion event will be delivered per CRTC in any case. It's just that *cough* someone forgot to include the CRTC ID in the event in the version of atomic support that first landed, so you get n events which each refer to _a_ CRTC, but userspace has no idea which. I don't think we need to refer too much to the caps. Realistically, I suspect everyone who ever tried to use a kernel which didn't have the CRTC ID in the completion event with atomic userspace is in this thread, apart from Maarten. Cheers, Daniel
