[PATCH 4/7] serial: 8250: Start rs485 after registering port if rs485 is enabled in probe

[Heiko Stuebner <heiko@sntech.de>]

From: Heiko Stuebner <heiko.stuebner@theobroma-systems.com>

Before registering a port 8250 drivers may read devicetree information
regarding rs485 emulation, but starting the em485 emulation at that point
would only keep the em485 structure in the template uart port.

Also at that point before the port is registered possible gpios for
rts/dtr are not acquired yet as well.

So simply check after acquiring the port if the rs485-enable flag is set
and start the config callback in that case.

Signed-off-by: Heiko Stuebner <heiko.stuebner@theobroma-systems.com>
---
 drivers/tty/serial/8250/8250_core.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index e682390ce0de..beab1c22b34d 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -1068,6 +1068,15 @@ int serial8250_register_8250_port(struct uart_8250_port *up)
 		if (up->dl_write)
 			uart->dl_write = up->dl_write;
 
+		if (uart->port.rs485_config &&
+		    (uart->port.rs485.flags & SER_RS485_ENABLED)) {
+			dev_dbg(uart->port.dev, "starting in rs485 mode\n");
+			ret = uart->port.rs485_config(&uart->port,
+						      &uart->port.rs485);
+			if (ret < 0)
+				goto out_unlock;
+		}
+
 		if (uart->port.type != PORT_8250_CIR) {
 			if (serial8250_isa_config != NULL)
 				serial8250_isa_config(0, &uart->port,
-- 
2.24.1