4.9-stable review patch. If anyone has any objections, please let me know.
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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;