[media] media/rc: Send sync space information on the lirc device

Userspace expects to see a long space before the first pulse is sent on
the lirc device. Currently, if a long time has passed and a new packet
is started, the lirc codec just returns and doesn't send anything. This
makes lircd ignore many perfectly valid signals unless they are sent in
quick sucession. When a reset event is delivered, we cannot know
anything about the duration of the space. But it should be safe to
assume it has been a long time and we just set the duration to maximum.

Signed-off-by: Austin Lund <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/rc/ir-lirc-codec.c

···
 		return -EINVAL;
 
 	/* Packet start */
-	if (ev.reset)
-		return 0;
+	if (ev.reset) {
+		/* Userspace expects a long space event before the start of
+		 * the signal to use as a sync.  This may be done with repeat
+		 * packets and normal samples.  But if a reset has been sent
+		 * then we assume that a long time has passed, so we send a
+		 * space with the maximum time value. */
+		sample = LIRC_SPACE(LIRC_VALUE_MASK);
+		IR_dprintk(2, "delivering reset sync space to lirc_dev\n");
 
 	/* Carrier reports */
-	if (ev.carrier_report) {
+	} else if (ev.carrier_report) {
 		sample = LIRC_FREQUENCY(ev.carrier);
 		IR_dprintk(2, "carrier report (freq: %d)\n", sample);