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    Subject[PATCH 4.14 23/75] serial: 8250_fintek: Fix rs485 disablement on invalid ioctl()
    Date
    4.14-stable review patch.  If anyone has any objections, please let me know.

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

    From: Lukas Wunner <lukas@wunner.de>


    [ 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@gmail.com>
    Cc: "Ji-Ze Hong (Peter Hong)" <hpeter@gmail.com>
    Signed-off-by: Lukas Wunner <lukas@wunner.de>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    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
    @@ -211,7 +211,7 @@ 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;


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