[Intel-gfx] [PATCH] drm/i915: Show debugfs dpcd read failure directly

[Chris Wilson]

Quoting Rodrigo Vivi (2018-07-20 18:41:10)
> Instead of using a backchannel if some dpcd read failed we
> can show that directly on debugfs output.
> 
> We are not returning an error because we might still want
> to know if sub-sequent reads works, but we shouldn't
> need to check 2 places to see why reg is not on the list.
 
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=106371
> Cc: Jani Nikula <jani.nikula at intel.com>
> Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan at intel.com>
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
-Chris