From: Hui Wang <hui.wang@xxxxxxxxxxxxx> commit 927728a34f11b5a27f4610bdb7068317d6fdc72a upstream. We tested RS485 function on an EVB which has SC16IS752, after finishing the test, we started the RS232 function test, but found the RTS is still working in the RS485 mode. That is because both startup and shutdown call port_update() to set the EFCR_REG, this will not clear the RS485 bits once the bits are set in the reconf_rs485(). To fix it, clear the RS485 bits in shutdown. Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Hui Wang <hui.wang@xxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20220308110042.108451-1-hui.wang@xxxxxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/tty/serial/sc16is7xx.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/drivers/tty/serial/sc16is7xx.c +++ b/drivers/tty/serial/sc16is7xx.c @@ -1055,10 +1055,12 @@ static void sc16is7xx_shutdown(struct ua /* Disable all interrupts */ sc16is7xx_port_write(port, SC16IS7XX_IER_REG, 0); - /* Disable TX/RX */ + /* Disable TX/RX, clear auto RS485 and RTS invert */ sc16is7xx_port_update(port, SC16IS7XX_EFCR_REG, SC16IS7XX_EFCR_RXDISABLE_BIT | - SC16IS7XX_EFCR_TXDISABLE_BIT, + SC16IS7XX_EFCR_TXDISABLE_BIT | + SC16IS7XX_EFCR_AUTO_RS485_BIT | + SC16IS7XX_EFCR_RTS_INVERT_BIT, SC16IS7XX_EFCR_RXDISABLE_BIT | SC16IS7XX_EFCR_TXDISABLE_BIT); Patches currently in stable-queue which might be from hui.wang@xxxxxxxxxxxxx are queue-4.9/serial-sc16is7xx-clear-rs485-bits-in-the-shutdown.patch
