In RS485 mode, the RTS pin is driven high by hardware when the transmitter is operating. This behaviour cannot be changed. This means that the driver should claim that it supports SER_RS485_RTS_ON_SEND and not SER_RS485_RTS_AFTER_SEND. Otherwise, when configuring the port with the SER_RS485_RTS_ON_SEND, one get the following warning: kern.warning kernel: atmel_usart_serial atmel_usart_serial.2.auto: ttyS1 (1): invalid RTS setting, using RTS_AFTER_SEND instead which is contradictory with what's really happening. Signed-off-by: Mathieu Othacehe <othacehe@xxxxxxx> --- drivers/tty/serial/atmel_serial.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c index 0a90964d6d107..09b246c9e389e 100644 --- a/drivers/tty/serial/atmel_serial.c +++ b/drivers/tty/serial/atmel_serial.c @@ -2514,7 +2514,7 @@ static const struct uart_ops atmel_pops = { }; static const struct serial_rs485 atmel_rs485_supported = { - .flags = SER_RS485_ENABLED | SER_RS485_RTS_AFTER_SEND | SER_RS485_RX_DURING_TX, + .flags = SER_RS485_ENABLED | SER_RS485_RTS_ON_SEND | SER_RS485_RX_DURING_TX, .delay_rts_before_send = 1, .delay_rts_after_send = 1, }; -- 2.45.2