linux-kernel - Serial 8250: clear the lsr_break

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Message-ID: <20070430220858.GA28890@localdomain>
Date:	Mon, 30 Apr 2007 17:08:59 -0500
From:	Corey Minyard <minyard@....org>
To:	Linux Kernel <linux-kernel@...r.kernel.org>,
	Russell King <rmk+lkml@....linux.org.uk>
Cc:	linux-serial@...r.kernel.org
Subject: Serial 8250: clear the lsr_break_flag at open

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@....org>

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 */

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