From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:46842 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933465AbeCWKQs (ORCPT ); Fri, 23 Mar 2018 06:16:48 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Moritz Fischer , Alexandre Belloni , Sasha Levin Subject: [PATCH 4.4 70/97] rtc: ds1374: wdt: Fix issue with timeout scaling from secs to wdt ticks Date: Fri, 23 Mar 2018 10:54:57 +0100 Message-Id: <20180323094201.536829633@linuxfoundation.org> In-Reply-To: <20180323094157.535925724@linuxfoundation.org> References: <20180323094157.535925724@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Moritz Fischer [ 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 Signed-off-by: Alexandre Belloni Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- 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;