This is a note to let you know that I've just added the patch titled serial: 8250_fintek: Fix rs485 disablement on invalid ioctl() to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: serial-8250_fintek-fix-rs485-disablement-on-invalid-ioctl.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From foo@baz Wed Dec 6 17:39:55 CET 2017 From: Lukas Wunner <lukas@xxxxxxxxx> Date: Sat, 28 Oct 2017 11:35:49 +0200 Subject: serial: 8250_fintek: Fix rs485 disablement on invalid ioctl() From: Lukas Wunner <lukas@xxxxxxxxx> [ Upstream commit 3236a965486ba0c6043cf2c7b51943d8b382ae29 ] This driver's ->rs485_config callback checks if SER_RS485_RTS_ON_SEND and SER_RS485_RTS_AFTER_SEND have the same value. If they do, it means the user has passed in invalid data with the TIOCSRS485 ioctl() since RTS must have a different polarity when sending and when not sending. In this case, rs485 mode is not enabled (the RS485_URA bit is not set in the RS485 Enable Register) and this is supposed to be signaled back to the user by clearing the SER_RS485_ENABLED bit in struct serial_rs485 ... except a missing tilde character is preventing that from happening. Fixes: 28e3fb6c4dce ("serial: Add support for Fintek F81216A LPC to 4 UART") Cc: Ricardo Ribalda Delgado <ricardo.ribalda@xxxxxxxxx> Cc: "Ji-Ze Hong (Peter Hong)" <hpeter@xxxxxxxxx> Signed-off-by: Lukas Wunner <lukas@xxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/tty/serial/8250/8250_fintek.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/tty/serial/8250/8250_fintek.c +++ b/drivers/tty/serial/8250/8250_fintek.c @@ -121,7 +121,7 @@ static int fintek_8250_rs485_config(stru if ((!!(rs485->flags & SER_RS485_RTS_ON_SEND)) == (!!(rs485->flags & SER_RS485_RTS_AFTER_SEND))) - rs485->flags &= SER_RS485_ENABLED; + rs485->flags &= ~SER_RS485_ENABLED; else config |= RS485_URA; Patches currently in stable-queue which might be from lukas@xxxxxxxxx are queue-4.9/serial-8250_fintek-fix-rs485-disablement-on-invalid-ioctl.patch