[media] adv7842: return 0 if no change in s_dv_timings

Return 0 if the new timings are equal to the current timings as
it caused extra cp-loss/lock interrupts.

Signed-off-by: Martin Bugge <marbugge@cisco.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

drivers/media/i2c/adv7842.c

@@ -1453,6 +1453,11 @@ static int adv7842_s_dv_timings(struct v4l2_subdev *sd,
 	if (state->mode == ADV7842_MODE_SDP)
 		return -ENODATA;
 
+	if (v4l2_match_dv_timings(&state->timings, timings, 0)) {
+		v4l2_dbg(1, debug, sd, "%s: no change\n", __func__);
+		return 0;
+	}
+
 	bt = &timings->bt;
 
 	if (!v4l2_valid_dv_timings(timings, adv7842_get_dv_timings_cap(sd),