drm/i915/gen9: Add WaDisableSkipCaching

Make sure that we never enable skip caching on gen9 by
accident.

References: HSD#2134698
Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1465309159-30531-17-git-send-email-mika.kuoppala@intel.com

drivers/gpu/drm/i915/intel_mocs.c

@@ -156,6 +156,16 @@ static bool get_mocs_settings(struct drm_i915_private *dev_priv,
 			  "Platform that should have a MOCS table does not.\n");
 	}
 
+	/* WaDisableSkipCaching:skl,bxt,kbl */
+	if (IS_GEN9(dev_priv)) {
+		int i;
+
+		for (i = 0; i < table->size; i++)
+			if (WARN_ON(table->table[i].l3cc_value &
+				    (L3_ESC(1) || L3_SCC(0x7))))
+				return false;
+	}
+
 	return result;
 }