drm/i915: Fix watermark calculation in self-refresh mode

For self-refresh mode WM calculation's "line time" should use
mode's htotal instead of hdisplay. "surface width" is the hdisplay
for display plane and 64 for cursor plane.

Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index d147ab2..7fba852 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -176,7 +176,8 @@
 	int (*get_display_clock_speed)(struct drm_device *dev);
 	int (*get_fifo_size)(struct drm_device *dev, int plane);
 	void (*update_wm)(struct drm_device *dev, int planea_clock,
-			  int planeb_clock, int sr_hdisplay, int pixel_size);
+			  int planeb_clock, int sr_hdisplay, int sr_htotal,
+			  int pixel_size);
 	/* clock updates for mode set */
 	/* cursor updates */
 	/* render clock increase/decrease */