On Tue, Sep 22, 2020 at 3:36 PM Marius Vlad <marius.vlad@xxxxxxxxxxxxx> wrote: > > On Fri, Jan 31, 2020 at 07:34:00AM +0000, Daniel Stone wrote: > > On Thu, 5 Jul 2018 at 11:21, Daniel Vetter <daniel.vetter@xxxxxxxx> wrote: > > > When doing an atomic modeset with ALLOW_MODESET drivers are allowed to > > > pull in arbitrary other resources, including CRTCs (e.g. when > > > reconfiguring global resources). > > > > > > But in nonblocking mode userspace has then no idea this happened, > > > which can lead to spurious EBUSY calls, both: > > > - when that other CRTC is currently busy doing a page_flip the > > > ALLOW_MODESET commit can fail with an EBUSY > > > - on the other CRTC a normal atomic flip can fail with EBUSY because > > > of the additional commit inserted by the kernel without userspace's > > > knowledge > > > > > > For blocking commits this isn't a problem, because everyone else will > > > just block until all the CRTC are reconfigured. Only thing userspace > > > can notice is the dropped frames without any reason for why frames got > > > dropped. > > > > > > Consensus is that we need new uapi to handle this properly, but no one > > > has any idea what exactly the new uapi should look like. As a stop-gap > > > plug this problem by demoting nonblocking commits which might cause > > > issues by including CRTCs not in the original request to blocking > > > commits. > Gentle ping. I've tried out Linus's master tree and, and like Pekka, > I've noticed this isn't integrated/added. Defacto the uapi we have now is that userspace needs to ignore "spurious" EBUSY. > Noticed this is fixing (also) DPMS when multiple outputs are in use. > Wondering if we can just use a _ONCE() variant instead of WARN_ON(). I'm seeing > the warning quite often. This would be a driver bug I think. That really shouldn't happen for normal page flips. -Daniel > > > > Thanks for writing this up Daniel, and for reminding me about it some > > time later as well ... > > > > Reviewed-by: Daniel Stone <daniels@xxxxxxxxxxxxx> > > > > Cheers, > > Daniel > > _______________________________________________ > > dri-devel mailing list > > dri-devel@xxxxxxxxxxxxxxxxxxxxx > > https://lists.freedesktop.org/mailman/listinfo/dri-devel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch
