drm/i915: Disable SAMPLER_STATE prefetching on all Gen11 steppings.

[ Upstream commit 248f883 ]

The Demand Prefetch workaround (binding table prefetching) only applies
to Icelake A0/B0.  But the Sampler Prefetch workaround needs to be
applied to all Gen11 steppings, according to a programming note in the
SARCHKMD documentation.

Using the Intel Gallium driver, I have seen intermittent failures in
the dEQP-GLES31.functional.copy_image.non_compressed.* tests.  After
applying this workaround, the tests reliably pass.

v2: Remove the overlap with a pre-production w/a

BSpec: 9663
Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: stable@vger.kernel.org
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190625090655.19220-1-chris@chris-wilson.co.uk
(cherry picked from commit f9a3938)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/gpu/drm/i915/intel_workarounds.c

@@ -1167,8 +1167,12 @@ rcs_engine_wa_init(struct intel_engine_cs *engine, struct i915_wa_list *wal)
  if (IS_ICL_REVID(i915, ICL_REVID_A0, ICL_REVID_B0))
  wa_write_or(wal,
  GEN7_SARCHKMD,
- GEN7_DISABLE_DEMAND_PREFETCH |
- GEN7_DISABLE_SAMPLER_PREFETCH);
+ GEN7_DISABLE_DEMAND_PREFETCH);
+
+ /* Wa_1606682166:icl */
+ wa_write_or(wal,
+ GEN7_SARCHKMD,
+ GEN7_DISABLE_SAMPLER_PREFETCH);
  }
 
  if (IS_GEN_RANGE(i915, 9, 11)) {