On Tue, Sep 22, 2020 at 4:14 PM Daniel Stone <daniel@xxxxxxxxxxxxx> wrote: > > On Tue, 22 Sep 2020 at 15:04, Daniel Vetter <daniel.vetter@xxxxxxxx> wrote: > > On Tue, Sep 22, 2020 at 3:36 PM Marius Vlad <marius.vlad@xxxxxxxxxxxxx> wrote: > > > 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. > > This really, really, really, bites. > > I think we need a guarantee that this never happens if ALLOW_MODESET > is always used in blocking mode, plus in future a cap we can use to > detect that we won't be getting spurious EBUSY events. > > I really don't want to ever paper over this, because it's one of the > clearest indications that userspace has its timing/signalling wrong. Ok so the hang-up last time around iirc was that I broke igt by making a few things more synchronous. Let's hope I'm not also breaking stuff with the WARN_ON ... New plan: - make this patch here only document existing behaviour and enforce it with the WARN_ON - new uapi would be behind a flag or something, with userspace and everything hanging off it. Thoughts? Cheers, Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch
