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

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 f9a393875d3af13cc3267477746608dadb7f17c1)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

diff --git a/drivers/gpu/drm/i915/gt/intel_workarounds.c b/drivers/gpu/drm/i915/gt/intel_workarounds.c
index 15e90fd2cfdc2e9882cfeff9f2e2e1e4a1ff1a7e..50c0060509a6817e00468c2e94d876165ce02bad 100644 (file)
--- a/drivers/gpu/drm/i915/gt/intel_workarounds.c
+++ b/drivers/gpu/drm/i915/gt/intel_workarounds.c
@@ -1258,8 +1258,12 @@ 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)) {