linux-kernel - [PATCH 3.16.y-ckt 44/58] [media] media/rc: Send sync space information on the lirc device

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Message-Id: <1424353948-31863-45-git-send-email-luis.henriques@canonical.com>
Date:	Thu, 19 Feb 2015 13:52:14 +0000
From:	Luis Henriques <luis.henriques@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Austin Lund <austin.lund@...il.com>,
	Mauro Carvalho Chehab <mchehab@....samsung.com>,
	Luis Henriques <luis.henriques@...onical.com>
Subject: [PATCH 3.16.y-ckt 44/58] [media] media/rc: Send sync space information on the lirc device

3.16.7-ckt7 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Austin Lund <austin.lund@...il.com>

commit a8f29e89f2b54fbf2c52be341f149bc195b63a8b upstream.

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 <austin.lund@...il.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@....samsung.com>
Cc: Austin Lund <austin.lund@...il.com>
Signed-off-by: Luis Henriques <luis.henriques@...onical.com>
---
 drivers/media/rc/ir-lirc-codec.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/media/rc/ir-lirc-codec.c b/drivers/media/rc/ir-lirc-codec.c
index d731da6c414d..2af2326ab3d2 100644
--- a/drivers/media/rc/ir-lirc-codec.c
+++ b/drivers/media/rc/ir-lirc-codec.c
@@ -42,11 +42,17 @@ static int ir_lirc_decode(struct rc_dev *dev, struct ir_raw_event ev)
 		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);
 
-- 
2.1.4

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