vsync_info
count = sfb->vsync_info.count;
ret = wait_event_interruptible_timeout(sfb->vsync_info.wait,
count != sfb->vsync_info.count,
init_waitqueue_head(&sfb->vsync_info.wait);
struct s3c_fb_vsync vsync_info;
sfb->vsync_info.count++;
wake_up_interruptible(&sfb->vsync_info.wait);