drm/i915: Implement Wa4x4STCOptimizationDisable:chv

Wa4x4STCOptimizationDisable got only implemented for BDW, but according
to the w/a database CHV needs it too, so add it.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Arun Siluvery <arun.siluvery@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_ringbuffer.c

@@ -851,6 +851,10 @@ static int chv_init_workarounds(struct intel_engine_cs *ring)
 	 */
 	WA_CLR_BIT_MASKED(CACHE_MODE_0_GEN7, HIZ_RAW_STALL_OPT_DISABLE);
 
+	/* Wa4x4STCOptimizationDisable:chv */
+	WA_SET_BIT_MASKED(CACHE_MODE_1,
+			  GEN8_4x4_STC_OPTIMIZATION_DISABLE);
+
 	/* Improve HiZ throughput on CHV. */
 	WA_SET_BIT_MASKED(HIZ_CHICKEN, CHV_HZ_8X8_MODE_IN_1X);