diff -Naur linux-awh3-3.4.orig/drivers/video/sunxi/disp2/disp/dev_fb.c linux-awh3-3.4/drivers/video/sunxi/disp2/disp/dev_fb.c
--- linux-awh3-3.4.orig/drivers/video/sunxi/disp2/disp/dev_fb.c	2015-12-28 00:57:55.744268698 -0800
+++ linux-awh3-3.4/drivers/video/sunxi/disp2/disp/dev_fb.c	2015-12-28 00:58:54.981872649 -0800
@@ -874,7 +874,7 @@

 	case FBIO_WAITFORVSYNC:
 	{
-		//ret = fb_wait_for_vsync(info);
+		ret = fb_wait_for_vsync(info);
 		break;
 	}