[PATCH 03/27] drm/arc: Actually bother with handling atomic events.

[Daniel Vetter]

On Wed, Jun 08, 2016 at 04:14:38PM +0200, Maarten Lankhorst wrote:
> Op 08-06-16 om 14:18 schreef Daniel Vetter:
> > The drm core has a nice ready-made helper for exactly the simple case
> > where it should fire on the next vblank.
> >
> > Note that arming the vblank event in _begin is probably too early, and
> > might easily result in the vblank firing too early, before the new set
> > of planes are actually disabled. But that's kinda a minor issue
> > compared to just outright hanging userspace.
> >
> > v2: Be more robust and either arm, when the CRTC is on, or just send
> > the event out right away.
> >
> > Cc: Carlos Palminha <palminha at synopsys.com>
> > Cc: Alexey Brodkin <abrodkin at synopsys.com>
> > Cc: linux-snps-arc at lists.infradead.org
> > Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
> Wouldn't it be better to do this in atomic_flush then?

I'm not going to fix up other people's drivers completely, just enough to
hopefully not break them. If arc also blocks vblank interrupts with the go
bit, then doing this in _begin is correct. Either way it needs hw-specific
knowledge to asses whether it's correct, since doing the vblank event
stuff in _flush is also racy without some prevention.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch