[Intel-gfx] [PATCH] drm/i915: Enforce read order into the hardware status page csb

[Chris Wilson]

Quoting Mika Kuoppala (2018-04-12 14:52:37)
> Read ordering on cpu can be out of order and speculative.

If it didn't include a barrier to prevent compiler mispeculation. rmb()
only applies to other CPU cores and not the GPU so this is entirely
hocus.
-Chris