Patch "watchdog: imx2_wdt: restore previous timeout after suspend+resume" has been added to the 4.9-stable tree

Patch "watchdog: imx2_wdt: restore previous timeout after suspend+resume" has been added to the 4.9-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    watchdog: imx2_wdt: restore previous timeout after suspend+resume

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     watchdog-imx2_wdt-restore-previous-timeout-after-suspend-resume.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 0be267255cef64e1c58475baa7b25568355a3816 Mon Sep 17 00:00:00 2001
From: Martin Kaiser <martin@kaiser.cx>
Date: Mon, 1 Jan 2018 18:26:47 +0100
Subject: watchdog: imx2_wdt: restore previous timeout after suspend+resume

From: Martin Kaiser <martin@kaiser.cx>

commit 0be267255cef64e1c58475baa7b25568355a3816 upstream.

When the watchdog device is suspended, its timeout is set to the maximum
value. During resume, the previously set timeout should be restored.
This does not work at the moment.

The suspend function calls

imx2_wdt_set_timeout(wdog, IMX2_WDT_MAX_TIME);

and resume reverts this by calling

imx2_wdt_set_timeout(wdog, wdog->timeout);

However, imx2_wdt_set_timeout() updates wdog->timeout. Therefore,
wdog->timeout is set to IMX2_WDT_MAX_TIME when we enter the resume
function.

Fix this by adding a new function __imx2_wdt_set_timeout() which
only updates the hardware settings. imx2_wdt_set_timeout() now calls
__imx2_wdt_set_timeout() and then saves the new timeout to
wdog->timeout.

During suspend, we call __imx2_wdt_set_timeout() directly so that
wdog->timeout won't be updated and we can restore the previous value
during resume. This approach makes wdog->timeout different from the
actual setting in the hardware which is usually not a good thing.
However, the two differ only while we're suspended and no kernel code is
running, so it should be ok in this case.

Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/watchdog/imx2_wdt.c |   20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

--- a/drivers/watchdog/imx2_wdt.c
+++ b/drivers/watchdog/imx2_wdt.c
@@ -169,15 +169,21 @@ static int imx2_wdt_ping(struct watchdog
 	return 0;
 }
 
-static int imx2_wdt_set_timeout(struct watchdog_device *wdog,
-				unsigned int new_timeout)
+static void __imx2_wdt_set_timeout(struct watchdog_device *wdog,
+				   unsigned int new_timeout)
 {
 	struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
 
-	wdog->timeout = new_timeout;
-
 	regmap_update_bits(wdev->regmap, IMX2_WDT_WCR, IMX2_WDT_WCR_WT,
 			   WDOG_SEC_TO_COUNT(new_timeout));
+}
+
+static int imx2_wdt_set_timeout(struct watchdog_device *wdog,
+				unsigned int new_timeout)
+{
+	__imx2_wdt_set_timeout(wdog, new_timeout);
+
+	wdog->timeout = new_timeout;
 	return 0;
 }
 
@@ -371,7 +377,11 @@ static int imx2_wdt_suspend(struct devic
 
 	/* The watchdog IP block is running */
 	if (imx2_wdt_is_running(wdev)) {
-		imx2_wdt_set_timeout(wdog, IMX2_WDT_MAX_TIME);
+		/*
+		 * Don't update wdog->timeout, we'll restore the current value
+		 * during resume.
+		 */
+		__imx2_wdt_set_timeout(wdog, IMX2_WDT_MAX_TIME);
 		imx2_wdt_ping(wdog);
 	}
 


Patches currently in stable-queue which might be from martin@kaiser.cx are

queue-4.9/watchdog-imx2_wdt-restore-previous-timeout-after-suspend-resume.patch