[Intel-gfx] [PATCH] drm/i915: Grab RPM wakeref around enabling vblank interrupts

[Chris Wilson]

On Fri, Oct 07, 2016 at 09:06:07PM +0300, Ville Syrjälä wrote:
> On Fri, Oct 07, 2016 at 02:50:32PM +0100, Chris Wilson wrote:
> > Whilst the vblank is configured to send an interrupt everytime, we need
> > to keep the device awake to process those interrupts.
> 
> If we can enable vblanks the pipe will be active, and thus we can't
> runtime suspend anyway. Also might_sleep() would be a problem.

Where is the pipe made active? Is it just having any mode is sufficient
to disable rpm? Will that always be the case?

Just tracing from the drm_wait_vblank ioctl to the mmio access it didn't
occur to me that there was a crtc wakeref.

Choice is either using something like intel_runtime_pm_get_noresume() or
/* CRTC must be kept alive whilst we enable vblanks */
assert_rpm...()

And possibly even using the seq check.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre