[Intel-gfx] [PATCH] drm/i915: Don't sanitize frame start delay if the pipe is off

[Chris Wilson]

Quoting Ville Syrjälä (2017-11-15 20:35:41)
> On Wed, Nov 15, 2017 at 08:17:21PM +0000, Chris Wilson wrote:
> > Quoting Ville Syrjala (2017-11-15 20:04:42)
> > > From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > > 
> > > Avoid touching PIPECONF in intel_sanitize_crtc() unless the pipe is
> > > actually on. Should cure some unclaimed register accesses.
> > 
> > While using crtc->active is consistent with other sanitization, is this
> > really a fix for unclaimed register access?
> > 
> > We should be holding all the powerwells at this moment in bringing up
> > the hw, right? So the only unclaimed access would be if the reg didn't
> > exist. So are we looking at an invalid cpu_transcoder?
> 
> I was thinking we'd have dropped the power references already. But
> I guess not. And that should definitely then give unclaimed register
> accesses during driver init.
> 
> I think these fails are in the "pretend display gets clobbered by GPU
> reset" path. And there we don't actually seem to grabbing the init power
> reference, which could well explain this. 

Hmm, it is in reset's __intel_dsiplay_resume() so that's a likely
candidate.

> Not sure we want to add the init power there either. Most of the readout
> code now has the power domain handling in place, so maybe we're close
> to being able to nuke the init power thing entirely?

But for reset, shouldn't we be taking the display powerwells in
intel_prepare_reset() or is that already there buried away in the
indirection?

Oh, that intel_display_set_init_power() definitely seems out of place
along reset.
-Chris