diff -ur /usr/src/linux/a/drivers/gpu/drm/i915/i915_suspend.c /usr/src/linux/b/drivers/gpu/drm/i915/i915_suspend.c
--- /usr/src/linux/a/drivers/gpu/drm/i915/i915_suspend.c	2012-10-29 21:19:13.843592586 +0100
+++ /usr/src/linux/b/drivers/gpu/drm/i915/i915_suspend.c	2012-10-29 21:32:32.217049378 +0100
@@ -29,6 +29,7 @@
 #include "i915_drm.h"
 #include "intel_drv.h"
 #include "i915_reg.h"
+#include <linux/delay.h>
 
 static bool i915_pipe_enabled(struct drm_device *dev, enum pipe pipe)
 {
@@ -877,6 +878,8 @@
 		I915_WRITE(IMR, dev_priv->saveIMR);
 	}
 
+	msleep (50);
+
 	/* Cache mode state */
 	I915_WRITE(CACHE_MODE_0, dev_priv->saveCACHE_MODE_0 | 0xffff0000);