[PATCH] drm: avoid spurious EBUSY due to nonblocking atomic modesets

[Daniel Vetter]

On Thu, May 14, 2020 at 08:40:21AM +0100, Daniel Stone wrote:
> On Thu, 14 May 2020 at 08:25, Daniel Vetter <daniel.vetter at ffwll.ch> wrote:
> > On Thu, May 14, 2020 at 9:18 AM Daniel Stone <daniel at fooishbar.org> wrote:
> > > On Thu, 14 May 2020 at 08:08, Daniel Vetter <daniel.vetter at ffwll.ch> wrote:
> > > I'd be very much in favour of putting the blocking down in the kernel
> > > at least until the kernel can give us a clear indication to tell us
> > > what's going on, and ideally which other resources need to be dragged
> > > in, in a way which is distinguishable from your compositor having
> > > broken synchronisation.
> >
> > We know, the patch already computes that ... So would be a matter of
> > exporting that to userspace. We have a mask of all additional crtc
> > that will get an event and will -EBUSY until that's done.
> 
> Yep, but unless and until that happens, could we please get this in?
> Given it would require uAPI changes, we'd need to modify all the
> compositors to work with the old path (random EBUSY) and the new path
> (predictable and obvious), so at least preserving the promise that
> per-CRTC updates are really independent would be good.

I haven't found the time to look at the intel-gfx-ci fail in igt nor
really think about that. Nor care enough to just hammer this ignoring ci,
since I didn't even get around to understand why the igt now fails If
someone else takes this over, happy to see it land.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch