From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754783AbaIWHrz (ORCPT ); Tue, 23 Sep 2014 03:47:55 -0400 Received: from mx0b-0016f401.pphosted.com ([67.231.156.173]:19218 "EHLO mx0b-0016f401.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752738AbaIWHry (ORCPT ); Tue, 23 Sep 2014 03:47:54 -0400 Date: Tue, 23 Sep 2014 15:45:01 +0800 From: Jisheng Zhang To: Guenter Roeck 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: <20140923154501.50dc8111@xhacker> In-Reply-To: <541D867C.6080407@roeck-us.net> References: <1411108199-1280-1-git-send-email-jszhang@marvell.com> <1411108199-1280-2-git-send-email-jszhang@marvell.com> <541D867C.6080407@roeck-us.net> X-Mailer: Claws Mail 3.10.1 (GTK+ 2.24.24; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:5.12.52,1.0.28,0.0.0000 definitions=2014-09-23_03:2014-09-23,2014-09-23,1970-01-01 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=7.0.1-1402240000 definitions=main-1409230081 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Dear Guenter, On Sat, 20 Sep 2014 06:51:56 -0700 Guenter Roeck wrote: > 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. > In patch V2, I initialize the TOP_INIT when setting TOP in function dw_wdt_set_top(), this also can fix the "reboot soon" problem. Could you please have a review again? Thanks, Jisheng