From 6f210c18c1c0f016772c8cd51ae12a02bfb9e7ef Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?David=20M=C3=BCller?= <d.mueller@elsoft.ch>
Date: Wed, 27 Apr 2016 11:58:32 +0200
Subject: [PATCH] serial: 8250_pci: fix divide error bug if baud rate is 0
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Since commit 21947ba654a6 ("serial: 8250_pci: replace switch-case by
formula"), the 8250 driver crashes in the byt_set_termios() function
with a divide error. This is caused by the fact that a baud rate of 0 (B0)
is not handled properly. Fix it by falling back to B9600 in this case.
Signed-off-by: David Müller <d.mueller@elsoft.ch>
Fixes: 21947ba654a6 ("serial: 8250_pci: replace switch-case by formula")
Cc: stable@vger.kernel.org
Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/tty/serial/8250/8250_pci.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/tty/serial/8250/8250_pci.c b/drivers/tty/serial/8250/8250_pci.c
index 98862aa5bb58..4eedd1da32e6 100644
--- a/drivers/tty/serial/8250/8250_pci.c
+++ b/drivers/tty/serial/8250/8250_pci.c
@@ -1377,6 +1377,9 @@ byt_set_termios(struct uart_port *p, struct ktermios *termios,
unsigned long m, n;
u32 reg;
+ /* Gracefully handle the B0 case: fall back to B9600 */
+ fuart = fuart ? fuart : 9600 * 16;
+
/* Get Fuart closer to Fref */
fuart *= rounddown_pow_of_two(fref / fuart);