diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 25972767129a..d4e57f9017db 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -1387,12 +1387,18 @@ static void uart_set_rs485_termination(struct uart_port *port,
 static int uart_rs485_config(struct uart_port *port)
 {
 	struct serial_rs485 *rs485 = &port->rs485;
+	unsigned long flags;
 	int ret;
 
+	if (!(rs485->flags & SER_RS485_ENABLED))
+		return 0;
+
 	uart_sanitize_serial_rs485(port, rs485);
 	uart_set_rs485_termination(port, rs485);
 
+	spin_lock_irqsave(&port->lock, flags);
 	ret = port->rs485_config(port, NULL, rs485);
+	spin_unlock_irqrestore(&port->lock, flags);
 	if (ret)
 		memset(rs485, 0, sizeof(*rs485));
 
@@ -2455,11 +2461,10 @@ int uart_resume_port(struct uart_driver *drv, struct uart_port *uport)
 			if (ret == 0) {
 				if (tty)
 					uart_change_line_settings(tty, state, NULL);
+				uart_rs485_config(uport);
 				spin_lock_irq(&uport->lock);
 				if (!(uport->rs485.flags & SER_RS485_ENABLED))
 					ops->set_mctrl(uport, uport->mctrl);
-				else
-					uart_rs485_config(uport);
 				ops->start_tx(uport);
 				spin_unlock_irq(&uport->lock);
 				tty_port_set_initialized(port, 1);
@@ -2568,10 +2573,10 @@ uart_configure_port(struct uart_driver *drv, struct uart_state *state,
 		port->mctrl &= TIOCM_DTR;
 		if (!(port->rs485.flags & SER_RS485_ENABLED))
 			port->ops->set_mctrl(port, port->mctrl);
-		else
-			uart_rs485_config(port);
 		spin_unlock_irqrestore(&port->lock, flags);
 
+		uart_rs485_config(port);
+
 		/*
 		 * If this driver supports console, and it hasn't been
 		 * successfully registered yet, try to re-register it.