diff --git a/drivers/video/pxafb.c b/drivers/video/pxafb.c
index 1e1c4ec0d3b935681cb6c9fce59cf2780d3b882c..ab689597f259bf81ca2e59ec6efe9b23760ca74e 100644
--- a/drivers/video/pxafb.c
+++ b/drivers/video/pxafb.c
@@ -794,11 +794,15 @@ static int pxafb_smart_thread(void *arg)
 		if (try_to_freeze())
 			continue;
 
+		mutex_lock(&fbi->ctrlr_lock);
+
 		if (fbi->state == C_ENABLE) {
 			inf->smart_update(&fbi->fb);
 			complete(&fbi->refresh_done);
 		}
 
+		mutex_unlock(&fbi->ctrlr_lock);
+
 		set_current_state(TASK_INTERRUPTIBLE);
 		schedule_timeout(30 * HZ / 1000);
 	}