When 8250 driver doesn't have its own hardware RS485 support and doesn't want to override rs485_config callback, then default serial8250_rs485_config is used. It just stores supplied by user-space config. Signed-off-by: Matwey V. Kornilov <matwey@xxxxxxxxxx> --- drivers/tty/serial/8250/8250_core.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c index 3912646..8f292da 100644 --- a/drivers/tty/serial/8250/8250_core.c +++ b/drivers/tty/serial/8250/8250_core.c @@ -395,6 +395,12 @@ static void serial8250_release_rsa_resource(struct uart_8250_port *up) } } #endif +static int serial8250_rs485_config(struct uart_port *port, + struct serial_rs485 *rs485) +{ + port->rs485 = *rs485; + return 0; +} static const struct uart_ops *base_ops; static struct uart_ops univ8250_port_ops; @@ -990,6 +996,10 @@ int serial8250_register_8250_port(struct uart_8250_port *up) uart->port.rs485 = up->port.rs485; uart->dma = up->dma; + /* Use software RS485 support when hardware one is not available */ + if (!(uart->capabilities & UART_CAP_HW485) && !uart->port.rs485_config) + uart->port.rs485_config = serial8250_rs485_config; + /* Take tx_loadsz from fifosize if it wasn't set separately */ if (uart->port.fifosize && !uart->tx_loadsz) uart->tx_loadsz = uart->port.fifosize; -- 2.6.2 -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html