diff --git a/drivers/serial/mpc52xx_uart.c b/drivers/serial/mpc52xx_uart.c
index 6459edc7f5c5..1b2cdc91c228 100644
--- a/drivers/serial/mpc52xx_uart.c
+++ b/drivers/serial/mpc52xx_uart.c
@@ -728,8 +728,7 @@ mpc52xx_uart_probe(struct platform_device *dev)
 
 	spin_lock_init(&port->lock);
 	port->uartclk	= __res.bi_ipbfreq / 2; /* Look at CTLR doc */
-	port->fifosize	= 255; /* Should be 512 ! But it can't be */
-	                       /* stored in a unsigned char       */
+	port->fifosize	= 512;
 	port->iotype	= UPIO_MEM;
 	port->flags	= UPF_BOOT_AUTOCONF |
 			  ( uart_console(port) ? 0 : UPF_IOREMAP );
diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index 17839e753e4c..3805f467b2f5 100644
--- a/drivers/serial/serial_core.c
+++ b/drivers/serial/serial_core.c
@@ -691,7 +691,8 @@ static int uart_set_info(struct uart_state *state,
 		    (new_serial.baud_base != port->uartclk / 16) ||
 		    (close_delay != state->close_delay) ||
 		    (closing_wait != state->closing_wait) ||
-		    (new_serial.xmit_fifo_size != port->fifosize) ||
+		    (new_serial.xmit_fifo_size &&
+		     new_serial.xmit_fifo_size != port->fifosize) ||
 		    (((new_flags ^ old_flags) & ~UPF_USR_MASK) != 0))
 			goto exit;
 		port->flags = ((port->flags & ~UPF_USR_MASK) |
@@ -796,7 +797,8 @@ static int uart_set_info(struct uart_state *state,
 	port->custom_divisor   = new_serial.custom_divisor;
 	state->close_delay     = close_delay;
 	state->closing_wait    = closing_wait;
-	port->fifosize         = new_serial.xmit_fifo_size;
+	if (new_serial.xmit_fifo_size)
+		port->fifosize = new_serial.xmit_fifo_size;
 	if (state->info->tty)
 		state->info->tty->low_latency =
 			(port->flags & UPF_LOW_LATENCY) ? 1 : 0;
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index bd14858121ea..966e2e8a1740 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -214,10 +214,11 @@ struct uart_port {
 	unsigned char __iomem	*membase;		/* read/write[bwl] */
 	unsigned int		irq;			/* irq number */
 	unsigned int		uartclk;		/* base uart clock */
-	unsigned char		fifosize;		/* tx fifo size */
+	unsigned int		fifosize;		/* tx fifo size */
 	unsigned char		x_char;			/* xon/xoff char */
 	unsigned char		regshift;		/* reg offset shift */
 	unsigned char		iotype;			/* io access style */
+	unsigned char		unused1;
 
 #define UPIO_PORT		(0)
 #define UPIO_HUB6		(1)