Serial 8250: clear the lsr_break_flag at open

From: Corey Minyard
Date: Mon Apr 30 2007 - 18:09:24 EST

Sorry for the double send, but I messed up on the subject. I'll
get used to mutt one of these days.

I think I've spotted a bug in the 8250 code, but I'm not really
sure. I'm having a hard time understanding why the lsr_break_flag
is necessary.

Subject: Serial 8250: clear the lsr_break_flag at open

The lsr_break_flag in the 8250 driver is not cleared when the port is
opened. This means that on a serial console, if a break has occurred
while the port is closed, the first call to receive_chars() will
result in a break being delivered at that point. Clear the flag at
open to fix the problem.

Signed-off-by: Corey Minyard <minyard@xxxxxxx>

Index: linux-2.6.21/drivers/serial/8250.c
--- linux-2.6.21.orig/drivers/serial/8250.c
+++ linux-2.6.21/drivers/serial/8250.c
@@ -1638,6 +1638,7 @@ static int serial8250_startup(struct uar

up->capabilities = uart_config[up->port.type].flags;
up->mcr = 0;
+ up->lsr_break_flag = 0;

if (up->port.type == PORT_16C950) {
/* Wake up and initialize UART */

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at