From db106df32d679db151b48a09543b03ee41cb2580 Mon Sep 17 00:00:00 2001
From: Peter Hurley <peter@hurleysoftware.com>
Date: Tue, 2 Sep 2014 17:39:15 -0400
Subject: serial: Fix send_xchar() handlers

START_CHAR() & STOP_CHAR() can be disabled if set to '\0'
(__DISABLED_CHAR).  UART drivers which define a send_xchar()
handler must not transmit __DISABLED_CHAR.

Document requirement.

Affected drivers:
sunsab
sunhv

cc: David S. Miller <davem@davemloft.net>
cc: <sparclinux@vger.kernel.org>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/tty/serial/sunhv.c | 3 +++
 1 file changed, 3 insertions(+)

(limited to 'drivers/tty/serial/sunhv.c')

diff --git a/drivers/tty/serial/sunhv.c b/drivers/tty/serial/sunhv.c
index 20521db2189f..25d43ce8b318 100644
--- a/drivers/tty/serial/sunhv.c
+++ b/drivers/tty/serial/sunhv.c
@@ -268,6 +268,9 @@ static void sunhv_send_xchar(struct uart_port *port, char ch)
 	unsigned long flags;
 	int limit = 10000;
 
+	if (ch == __DISABLED_CHAR)
+		return;
+
 	spin_lock_irqsave(&port->lock, flags);
 
 	while (limit-- > 0) {
-- 
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