diff --git a/drivers/tty/serial/8250/8250.c b/drivers/tty/serial/8250/8250.c
index 0d771ec16750..e2ac25a037ef 100644
--- a/drivers/tty/serial/8250/8250.c
+++ b/drivers/tty/serial/8250/8250.c
@@ -1911,9 +1911,12 @@ static int serial8250_startup(struct uart_port *port)
 	if (port->type == PORT_8250_CIR)
 		return -ENODEV;
 
-	port->fifosize = uart_config[up->port.type].fifo_size;
-	up->tx_loadsz = uart_config[up->port.type].tx_loadsz;
-	up->capabilities = uart_config[up->port.type].flags;
+	if (!port->fifosize)
+		port->fifosize = uart_config[port->type].fifo_size;
+	if (!up->tx_loadsz)
+		up->tx_loadsz = uart_config[port->type].tx_loadsz;
+	if (!up->capabilities)
+		up->capabilities = uart_config[port->type].flags;
 	up->mcr = 0;
 
 	if (port->iotype != up->cur_iotype)
@@ -2746,9 +2749,12 @@ static void
 serial8250_init_fixed_type_port(struct uart_8250_port *up, unsigned int type)
 {
 	up->port.type = type;
-	up->port.fifosize = uart_config[type].fifo_size;
-	up->capabilities = uart_config[type].flags;
-	up->tx_loadsz = uart_config[type].tx_loadsz;
+	if (!up->port.fifosize)
+		up->port.fifosize = uart_config[type].fifo_size;
+	if (!up->tx_loadsz)
+		up->tx_loadsz = uart_config[type].tx_loadsz;
+	if (!up->capabilities)
+		up->capabilities = uart_config[type].flags;
 }
 
 static void __init
@@ -3182,6 +3188,10 @@ int serial8250_register_8250_port(struct uart_8250_port *up)
 		uart->bugs		= up->bugs;
 		uart->port.mapbase      = up->port.mapbase;
 		uart->port.private_data = up->port.private_data;
+		uart->port.fifosize	= up->port.fifosize;
+		uart->tx_loadsz		= up->tx_loadsz;
+		uart->capabilities	= up->capabilities;
+
 		if (up->port.dev)
 			uart->port.dev = up->port.dev;