[Intel-gfx] [RFC] drm/i915: Rework "Potential atomic update error" to handle PSR exit

[Chris Wilson]

Quoting Ville Syrjälä (2018-04-27 13:41:42)
> On Thu, Apr 26, 2018 at 08:09:56PM -0700, Tarun Vyas wrote:
> > On a second thought, I was doing it wrong in the initial RFC. Can't do a wait_for_register with irqs disabled by local_irq_disable(). So, will have to *poll* the PSR_STATE, but will that be desirable ?
> 
> Do it before disabling the irqs? As long as we prevent it from
> re-entering PSR after the wait it should be safe. Maybe the vblank irq
> is the best way to prevent the re-entry?

There's also an atomic variant of wait_for_register. But if we don't
need to wait with irqs off, don't.
-Chris