From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756284AbaITNw0 (ORCPT ); Sat, 20 Sep 2014 09:52:26 -0400 Received: from bh-25.webhostbox.net ([208.91.199.152]:52338 "EHLO bh-25.webhostbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754054AbaITNwY (ORCPT ); Sat, 20 Sep 2014 09:52:24 -0400 Message-ID: <541D867C.6080407@roeck-us.net> Date: Sat, 20 Sep 2014 06:51:56 -0700 From: Guenter Roeck User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.0 MIME-Version: 1.0 To: Jisheng Zhang , wim@iguana.be CC: 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 References: <1411108199-1280-1-git-send-email-jszhang@marvell.com> <1411108199-1280-2-git-send-email-jszhang@marvell.com> In-Reply-To: <1411108199-1280-2-git-send-email-jszhang@marvell.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-Authenticated_sender: linux@roeck-us.net X-OutGoing-Spam-Status: No, score=-1.0 X-CTCH-PVer: 0000001 X-CTCH-Spam: Unknown X-CTCH-VOD: Unknown X-CTCH-Flags: 0 X-CTCH-RefID: str=0001.0A020203.541D8697.010E,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0 X-CTCH-Score: 0.000 X-CTCH-ScoreCust: 0.000 X-CTCH-Rules: X-CTCH-SenderID: linux@roeck-us.net X-CTCH-SenderID-Flags: 0 X-CTCH-SenderID-TotalMessages: 2 X-CTCH-SenderID-TotalSpam: 0 X-CTCH-SenderID-TotalSuspected: 0 X-CTCH-SenderID-TotalConfirmed: 0 X-CTCH-SenderID-TotalBulk: 0 X-CTCH-SenderID-TotalVirus: 0 X-CTCH-SenderID-TotalRecipients: 0 X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - bh-25.webhostbox.net X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - roeck-us.net X-Get-Message-Sender-Via: bh-25.webhostbox.net: mailgid no entry from get_relayhosts_entry X-Source: X-Source-Args: X-Source-Dir: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/18/2014 11:29 PM, Jisheng Zhang wrote: > The TOP_INIT may be zero, so the timeout period may be very short after > 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); > writel(WDOG_CONTROL_REG_WDT_EN_MASK, > dw_wdt.regs + WDOG_CONTROL_REG_OFFSET); > + dw_wdt_keepalive(); > } > > dw_wdt_set_next_heartbeat(); > After getting access to the datasheet, I concluded that this fix is wrong or at least more risky than necessary. The datasheet states that top_init, ie bit 4-7 of the wdt_torr register, needs to be initialized with the desired timeout period prior to enabling the watchdog. dw_wdt_set_top() sets it to 0 instead, ie to the lowest possible timeout period. Guenter