[Intel-gfx] [PATCH 1/2] drm/i915: Try to suppress more spurious PCH underruns on ILK-IVB

[Chris Wilson]

Quoting Ville Syrjala (2018-05-24 20:04:05)
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> My ILK seems to generate a spurious PCH underrun with most interlaced
> HDMI modes. Add a second vblank wait to avoid it.

Fwiw, a second vblank because of interlacing is very believable.
 
> We have seen some spurious PCH underruns still in CI as well, some
> of which seem to be progressive DP. The logs also point towards some
> spurious underrins with progressive HDMI on SNB. While I don't have
> a solid explanation for those let's try to kill all the birds with one
> stone and always do the double wait.
> 
> Buzilla: https://bugs.freedesktop.org/show_bug.cgi?id=106387
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
Acked-by: Chris Wilson <chris at chris-wilson.co.uk>

No point waiting for a vblank worker? ;)
-Chris