On 8/17/23 12:37, Michel Dänzer wrote: > On 8/15/23 20:57, André Almeida wrote: >> From: Pekka Paalanen <pekka.paala...@collabora.com> >> >> Specify how the atomic state is maintained between userspace and >> kernel, plus the special case for async flips. >> >> Signed-off-by: Pekka Paalanen <pekka.paala...@collabora.com> >> Signed-off-by: André Almeida <andrealm...@igalia.com> > > [...] > >> +An atomic commit with the flag DRM_MODE_PAGE_FLIP_ASYNC is allowed to >> +effectively change only the FB_ID property on any planes. No-operation >> changes >> +are ignored as always. [...] > > During the hackfest in Brno, it was mentioned that a commit which re-sets the > same FB_ID could actually have an effect with VRR: It could trigger scanout > of the next frame before vertical blank has reached its maximum duration. > Some kind of mechanism is required for this in order to allow user space to > perform low frame rate compensation.
That said, it doesn't make too much sense to use DRM_MODE_PAGE_FLIP_ASYNC for this, since it won't have any effect outside of vertical blank anyway. -- Earthling Michel Dänzer | https://redhat.com Libre software enthusiast | Mesa and Xwayland developer
