Patch "rtc: ds1374: wdt: Fix issue with timeout scaling from secs to wdt ticks" has been added to the 4.4-stable tree

Patch "rtc: ds1374: wdt: Fix issue with timeout scaling from secs to wdt ticks" has been added to the 4.4-stable tree

[gregkh]

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

    rtc: ds1374: wdt: Fix issue with timeout scaling from secs to wdt ticks

to the 4.4-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:
     rtc-ds1374-wdt-fix-issue-with-timeout-scaling-from-secs-to-wdt-ticks.patch
and it can be found in the queue-4.4 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 foo@baz Thu Mar 22 14:57:32 CET 2018
From: Moritz Fischer <mdf@kernel.org>
Date: Mon, 24 Apr 2017 15:05:11 -0700
Subject: rtc: ds1374: wdt: Fix issue with timeout scaling from secs to wdt ticks

From: Moritz Fischer <mdf@kernel.org>


[ Upstream commit 453d0744f6c6ca3f9749b8c57c2e85b5b9f52514 ]

The issue is that the internal counter that triggers the watchdog reset
is actually running at 4096 Hz instead of 1Hz, therefore the value
given by userland (in sec) needs to be multiplied by 4096 to get the
correct behavior.

Fixes: 920f91e50c5b ("drivers/rtc/rtc-ds1374.c: add watchdog support")
Signed-off-by: Moritz Fischer <mdf@kernel.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/rtc/rtc-ds1374.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

--- a/drivers/rtc/rtc-ds1374.c
+++ b/drivers/rtc/rtc-ds1374.c
@@ -527,6 +527,10 @@ static long ds1374_wdt_ioctl(struct file
 		if (get_user(new_margin, (int __user *)arg))
 			return -EFAULT;
 
+		/* the hardware's tick rate is 4096 Hz, so
+		 * the counter value needs to be scaled accordingly
+		 */
+		new_margin <<= 12;
 		if (new_margin < 1 || new_margin > 16777216)
 			return -EINVAL;
 
@@ -535,7 +539,8 @@ static long ds1374_wdt_ioctl(struct file
 		ds1374_wdt_ping();
 		/* fallthrough */
 	case WDIOC_GETTIMEOUT:
-		return put_user(wdt_margin, (int __user *)arg);
+		/* when returning ... inverse is true */
+		return put_user((wdt_margin >> 12), (int __user *)arg);
 	case WDIOC_SETOPTIONS:
 		if (copy_from_user(&options, (int __user *)arg, sizeof(int)))
 			return -EFAULT;


Patches currently in stable-queue which might be from mdf@kernel.org are

queue-4.4/rtc-ds1374-wdt-fix-stop-start-ioctl-always-returning-einval.patch
queue-4.4/rtc-ds1374-wdt-fix-issue-with-timeout-scaling-from-secs-to-wdt-ticks.patch