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

[Chris Wilson]

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?
-Chris