[PATCH 5.10 21/93] media: ir_toy: prevent device from hanging during transmit

Greg Kroah-Hartman
2021-10-04T13:23:05Z

From: Sean Young <sean@mess.org>

commit f0c15b360fb65ee39849afe987c16eb3d0175d0d upstream.

If the IR Toy is receiving IR while a transmit is done, it may end up
hanging. We can prevent this from happening by re-entering sample mode
just before issuing the transmit command.

Link: https://github.com/bengtmartensson/HarcHardware/discussions/25

Cc: stable@vger.kernel.org
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/media/rc/ir_toy.c | 21 ++++++++++++++++++++-
1 file changed, 20 insertions(+), 1 deletion(-)

--- a/drivers/media/rc/ir_toy.c
+++ b/drivers/media/rc/ir_toy.c
@@ -24,6 +24,7 @@ static const u8 COMMAND_VERSION[] = { 'v
// End transmit and repeat reset command so we exit sump mode
static const u8 COMMAND_RESET[] = { 0xff, 0xff, 0, 0, 0, 0, 0 };
static const u8 COMMAND_SMODE_ENTER[] = { 's' };
+static const u8 COMMAND_SMODE_EXIT[] = { 0 };
static const u8 COMMAND_TXSTART[] = { 0x26, 0x24, 0x25, 0x03 };

#define REPLY_XMITCOUNT 't'
@@ -309,12 +310,30 @@ static int irtoy_tx(struct rc_dev *rc, u
buf[i] = cpu_to_be16(v);
}

- buf[count] = cpu_to_be16(0xffff);
+ buf[count] = 0xffff;

irtoy->tx_buf = buf;
irtoy->tx_len = size;
irtoy->emitted = 0;

+ // There is an issue where if the unit is receiving IR while the
+ // first TXSTART command is sent, the device might end up hanging
+ // with its led on. It does not respond to any command when this
+ // happens. To work around this, re-enter sample mode.
+ err = irtoy_command(irtoy, COMMAND_SMODE_EXIT,
+ sizeof(COMMAND_SMODE_EXIT), STATE_RESET);
+ if (err) {
+ dev_err(irtoy->dev, "exit sample mode: %d\n", err);
+ return err;
+ }
+
+ err = irtoy_command(irtoy, COMMAND_SMODE_ENTER,
+ sizeof(COMMAND_SMODE_ENTER), STATE_COMMAND);
+ if (err) {
+ dev_err(irtoy->dev, "enter sample mode: %d\n", err);
+ return err;
+ }
+
err = irtoy_command(irtoy, COMMAND_TXSTART, sizeof(COMMAND_TXSTART),
STATE_TX);
kfree(buf);