On 2/19/26 16:56, Michele Palazzi wrote: > On 2/19/26 14:59, Michel Dänzer wrote: >> Can't the issue be solved by fixing the pflip_status handling in the vblank >> handler? >> I guess that might also hit the second race condition: >> >>> - If vblank is disabled by the off-delay timer before the handler >>> runs, the PENDING cursor event is never delivered and the commit hangs. >> >> That sounds like the drm_crtc_vblank_get/put handling might be incorrect in >> amdgpu_dm. >> >> In a nutshell, the vblank interrupt is kept enabled as long as there have >> been more >> drm_crtc_vblank_get calls than _put ones for the CRTC. I.e. amdgpu_dm needs >> to call the former under circumstances where it needs the interrupt to be >> on, and the latter only once it's no longer needed for those circumstances >> (in this case when sending the event). > > The get/put pairing seems correct,
"If vblank is disabled by the off-delay timer before the handler runs, the PENDING cursor event is never delivered" indicates otherwise. If the handling was correct, the vblank interrupt should never be disabled before the handler runs. > the issue is that cursor and pflip share the same acrtc->event slot, so the > pflip_status check in the vblank handler can race. Adding a dedicated > cursor_event field, separate from event used by pflip, could maybe solve the > whole thing? Maybe? If the vblank event handler never needs to send an event for a flip. -- Earthling Michel Dänzer \ GNOME / Xwayland / Mesa developer https://redhat.com \ Libre software enthusiast
