From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757782AbaISR1j (ORCPT ); Fri, 19 Sep 2014 13:27:39 -0400 Received: from mail-pa0-f50.google.com ([209.85.220.50]:56064 "EHLO mail-pa0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757413AbaISR1h (ORCPT ); Fri, 19 Sep 2014 13:27:37 -0400 Date: Fri, 19 Sep 2014 10:27:32 -0700 From: Guenter Roeck To: Jisheng Zhang Cc: wim@iguana.be, linux-watchdog@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH 1/2] watchdog: dw_wdt: restart the counter immediately after enabling WDT Message-ID: <20140919172732.GA716@roeck-us.net> References: <1411108199-1280-1-git-send-email-jszhang@marvell.com> <1411108199-1280-2-git-send-email-jszhang@marvell.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1411108199-1280-2-git-send-email-jszhang@marvell.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Sep 19, 2014 at 02:29:58PM +0800, Jisheng Zhang wrote: > The TOP_INIT may be zero, so the timeout period may be very short after What is TOP_INIT ? > initialization is done, thus the system may be reset soon after enabling. > We fix this problem by restarting the counter immediately after enabling > WDT. > > Signed-off-by: Jisheng Zhang > --- > drivers/watchdog/dw_wdt.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/watchdog/dw_wdt.c b/drivers/watchdog/dw_wdt.c > index 9f21029..ad0619d 100644 > --- a/drivers/watchdog/dw_wdt.c > +++ b/drivers/watchdog/dw_wdt.c > @@ -146,6 +146,7 @@ static int dw_wdt_open(struct inode *inode, struct file *filp) > dw_wdt_set_top(DW_WDT_MAX_TOP); This sets the timeout to the maximum, so I guess there must be some other event/register (TOP_INIT ?) which can be zero. > writel(WDOG_CONTROL_REG_WDT_EN_MASK, > dw_wdt.regs + WDOG_CONTROL_REG_OFFSET); What guarantees that the reset didn't already happen by the time the keepalive call is executed ? Does this change fix the problem, or does it just make it more unlikely to be seen ? Thanks, Guenter > + dw_wdt_keepalive(); > } > > dw_wdt_set_next_heartbeat(); > -- > 2.1.0 >