On Friday, December 11th, 2020 at 2:50 PM, Pekka Paalanen <ppaalanen@xxxxxxxxx> wrote: > is there a reason why one cannot have more primary planes than CRTCs in > existence? > > Daniel implied that in <20201209003637.GK401619@phenom.ffwll.local>, > but I didn't get the reason for it yet. > > E.g. if all your planes are interchangeable in the sense that you can > turn on a CRTC with any one of them, would one not then expose all the > planes as "Primary"? I'm thinking of primary as a hint for simple user-space: "you can likely light up a CRTC if you attach this plane and don't do anything crazy". For anything more complicated, user-space uses atomic commits and can completely ignore whether a plane is primary, cursor or overlay. > If the planes have other differences, like supported formats or > scaling, then marking them all "Primary" would let userspace know that > it can pick any plane with the suitable properties and expect to turn > on the CRTC with it. That's interesting, but I'd bet no user-space does that. If new user-space wants to, it's better to rely on test-only commits instead. > Or does marking a plane as "Primary" imply something else too, like > "cannot scale"? I think Weston does make this assumption in an attempt > to hit fewer causes for failure. No, AFAIK "Primary" doesn't imply something else, e.g. on amdgpu you can do scaling on the primary plane. _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
