drm/i915/bxt: Broxton DDB is 512 blocks

Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Reviewed-by: Antti Koskipää <antti.koskipaa@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_pm.c

@@ -2538,6 +2538,7 @@ static bool ilk_disable_lp_wm(struct drm_device *dev)
  */
 
 #define SKL_DDB_SIZE		896	/* in blocks */
+#define BXT_DDB_SIZE		512
 
 static void
 skl_ddb_get_pipe_allocation_limits(struct drm_device *dev,
@@ -2556,6 +2557,9 @@ skl_ddb_get_pipe_allocation_limits(struct drm_device *dev,
 		return;
 	}
 
+	if (IS_BROXTON(dev))
+		ddb_size = BXT_DDB_SIZE;
+	else
 		ddb_size = SKL_DDB_SIZE;
 
 	ddb_size -= 4; /* 4 blocks for bypass path allocation */