On 2021-03-04 4:09 p.m., Kazlauskas, Nicholas wrote: > On 2021-03-04 4:05 a.m., Michel Dänzer wrote: >> On 2021-03-03 8:17 p.m., Daniel Vetter wrote: >>> On Wed, Mar 3, 2021 at 5:53 PM Michel Dänzer <michel@xxxxxxxxxxx> wrote: >>>> >>>> Moreover, in the same scenario plus an overlay plane enabled with a >>>> HW cursor compatible format, if the FB bound to the overlay plane is >>>> destroyed, the common DRM code will attempt to disable the overlay >>>> plane, but dm_check_crtc_cursor will reject that now. I can't remember >>>> exactly what the result is, but AFAIR it's not pretty. >>> >>> CRTC gets disabled instead. That's why we went with the "always >>> require primary plane" hack. I think the only solution here would be >>> to enable the primary plane (but not in userspace-visible state, so >>> this needs to be done in the dc derived state objects only) that scans >>> out black any time we're in such a situation with cursor with no >>> planes. >> >> This is about a scenario described by Nicholas earlier: >> >> Cursor Plane - ARGB8888 >> >> Overlay Plane - ARGB8888 Desktop/UI with cutout for video >> >> Primary Plane - NV12 video >> >> And destroying the FB bound to the overlay plane. The fallback to disable >> the CRTC in atomic_remove_fb only kicks in for the primary plane, so it >> wouldn't in this case and would fail. Which would in turn trigger the >> WARN in drm_framebuffer_remove (and leave the overlay plane scanning out >> from freed memory?). >> >> >> The cleanest solution might be not to allow any formats incompatible with >> the HW cursor for the primary plane. > > Legacy X userspace doesn't use overlays but Chrome OS does. > > This would regress ChromeOS MPO support because it relies on the NV12 > video plane being on the bottom. Could it use the NV12 overlay plane below the ARGB primary plane? > When ChromeOS disables MPO it doesn't do it plane by plane, it does it > in one go from NV12+ARGB8888 -> ARGB88888. Even so, we cannot expect all user space to do the same, and we cannot allow any user space to trigger a WARN and scanout from freed memory. -- Earthling Michel Dänzer | https://redhat.com Libre software enthusiast | Mesa and X developer _______________________________________________ amd-gfx mailing list amd-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/amd-gfx
