There are rs485 transceivers (e.g. MAX13487E/MAX13488E) which automatically disable or enable the driver and receiver to keep the bus in the correct state. In these cases we don't need a GPIO for flow control.
Fixes: 4a0ac0f55b18 ("OMAP: add RS485 support") Signed-off-by: Dario Binacchi <dario...@libero.it> --- Changes in v2: - Add 'Fixes' tag drivers/tty/serial/omap-serial.c | 12 ++++-------- 1 file changed, 4 insertions(+), 8 deletions(-) diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c index 76b94d0ff586..1583e93b2202 100644 --- a/drivers/tty/serial/omap-serial.c +++ b/drivers/tty/serial/omap-serial.c @@ -302,7 +302,8 @@ static void serial_omap_stop_tx(struct uart_port *port) serial_out(up, UART_OMAP_SCR, up->scr); res = (port->rs485.flags & SER_RS485_RTS_AFTER_SEND) ? 1 : 0; - if (gpiod_get_value(up->rts_gpiod) != res) { + if (up->rts_gpiod && + gpiod_get_value(up->rts_gpiod) != res) { if (port->rs485.delay_rts_after_send > 0) mdelay( port->rs485.delay_rts_after_send); @@ -411,7 +412,7 @@ static void serial_omap_start_tx(struct uart_port *port) /* if rts not already enabled */ res = (port->rs485.flags & SER_RS485_RTS_ON_SEND) ? 1 : 0; - if (gpiod_get_value(up->rts_gpiod) != res) { + if (up->rts_gpiod && gpiod_get_value(up->rts_gpiod) != res) { gpiod_set_value(up->rts_gpiod, res); if (port->rs485.delay_rts_before_send > 0) mdelay(port->rs485.delay_rts_before_send); @@ -1407,18 +1408,13 @@ serial_omap_config_rs485(struct uart_port *port, struct serial_rs485 *rs485) /* store new config */ port->rs485 = *rs485; - /* - * Just as a precaution, only allow rs485 - * to be enabled if the gpio pin is valid - */ if (up->rts_gpiod) { /* enable / disable rts */ val = (port->rs485.flags & SER_RS485_ENABLED) ? SER_RS485_RTS_AFTER_SEND : SER_RS485_RTS_ON_SEND; val = (port->rs485.flags & val) ? 1 : 0; gpiod_set_value(up->rts_gpiod, val); - } else - port->rs485.flags &= ~SER_RS485_ENABLED; + } /* Enable interrupts */ up->ier = mode; -- 2.17.1