On Wed, Jan 16, 2013 at 6:36 AM, Daniel Vetter daniel@ffwll.ch wrote:
On Wed, Jan 16, 2013 at 11:01 AM, Thierry Reding thierry.reding@avionic-design.de wrote:
drm_events_release() should be enough to clean up the events, but I suspect the reason why Laurent put that code in was that the drm_crtc private data still has a reference to the event and needs to clear it. Otherwise the next page flip won't be scheduled because .page_flip() would return -EBUSY.
Hm, indeed we seem to have a nice bug in most drivers there :(
However, it seems like {tegra_dc,shmob_drm_crtc}_cancel_page_flip() could both be simplified a lot and just set their event to NULL. Then again, maybe keeping a separate reference isn't all that useful. Maybe the better thing to do here is iterate over the list of pending VBLANK events in *_finish_page_flip() and process each of them? That would allow more than one user-space process to queue page flips.
I think we need a slightly more generally useful solution, since most drivers are currently broken. I've read a bit through the code, but short of refcounting drm events and adding event->file_priv checks at relevent places I don't see a sane solution ... And even that one is rather invasive. Do you have an idea? Imo doing the cleanup in each driver will be rather error-prone, and since usually kms clients wait for flips to complete, also guaranteed to be little tested.
I suppose we could move the *pending_vblank_event to 'struct drm_crtc'.. I think probably all/most drivers need the same thing anyway. If a driver needs to do something special, it could just never set crtc->pending_vblank_event and instead do it's own cleanup.
BR, -R
-Daniel
Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/dri-devel