[3.16.y-ckt stable] Patch "serial: samsung: wait for transfer completion before clock disable" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    serial: samsung: wait for transfer completion before clock disable

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt4.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 6af93e6c73413e6af9e5e6bac7d2f8b0eec60ca8 Mon Sep 17 00:00:00 2001
From: Robert Baldyga <r.baldyga at samsung.com>
Date: Mon, 24 Nov 2014 07:56:21 +0100
Subject: serial: samsung: wait for transfer completion before clock disable

commit 1ff383a4c3eda8893ec61b02831826e1b1f46b41 upstream.

This patch adds waiting until transmit buffer and shifter will be empty
before clock disabling.

Without this fix it's possible to have clock disabled while data was
not transmited yet, which causes unproper state of TX line and problems
in following data transfers.

Signed-off-by: Robert Baldyga <r.baldyga at samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/tty/serial/samsung.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/tty/serial/samsung.c b/drivers/tty/serial/samsung.c
index c1d3ebdf3b97..7268409dfc68 100644
--- a/drivers/tty/serial/samsung.c
+++ b/drivers/tty/serial/samsung.c
@@ -567,11 +567,15 @@ static void s3c24xx_serial_pm(struct uart_port *port, unsigned int level,
 			      unsigned int old)
 {
 	struct s3c24xx_uart_port *ourport = to_ourport(port);
+	int timeout = 10000;

 	ourport->pm_level = level;

 	switch (level) {
 	case 3:
+		while (--timeout && !s3c24xx_serial_txempty_nofifo(port))
+			udelay(100);
+
 		if (!IS_ERR(ourport->baudclk))
 			clk_disable_unprepare(ourport->baudclk);

--
2.1.4