media: ir_toy: prevent device from hanging during transmit

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>

diff --git a/drivers/media/rc/ir_toy.c b/drivers/media/rc/ir_toy.c
index 3e729a17b35ff9dab6651c150d2230d35f4c62df..48d52baec1a1c981f2cd0122d8fe03911c7373cd 100644 (file)
--- 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, uint *txbuf, uint count)
                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);