drm/i915/gen9: Implement Wa4x4STCOptimizationDisable

Move Wa4x4STCOptimizationDisable to gen9_init_workarounds

v2: rebase

Signed-off-by: Nick Hoath <nicholas.hoath@intel.com>
Reviewed-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
index 2ab447c..e35b341 100644
--- a/drivers/gpu/drm/i915/intel_ringbuffer.c
+++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
@@ -902,6 +902,9 @@
 				  GEN9_ENABLE_YV12_BUGFIX);
 	}
 
+	/* Wa4x4STCOptimizationDisable:skl */
+	WA_SET_BIT_MASKED(CACHE_MODE_1, GEN8_4x4_STC_OPTIMIZATION_DISABLE);
+
 	return 0;
 }