From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from bh-25.webhostbox.net ([208.91.199.152]:43574 "EHLO bh-25.webhostbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752146AbbEHBrt (ORCPT ); Thu, 7 May 2015 21:47:49 -0400 Received: from mailnull by bh-25.webhostbox.net with sa-checked (Exim 4.85) (envelope-from ) id 1YqXOG-002yfC-Kh for linux-watchdog@vger.kernel.org; Fri, 08 May 2015 01:47:48 +0000 Message-ID: <554C15C2.60802@roeck-us.net> Date: Thu, 07 May 2015 18:47:46 -0700 From: Guenter Roeck MIME-Version: 1.0 To: Doug Anderson , wim@iguana.be CC: jszhang@marvell.com, linux-watchdog@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] watchdog: dw_wdt: keepalive the watchdog at write time References: <1431036564-4189-1-git-send-email-dianders@chromium.org> <1431036564-4189-2-git-send-email-dianders@chromium.org> In-Reply-To: <1431036564-4189-2-git-send-email-dianders@chromium.org> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-watchdog-owner@vger.kernel.org List-Id: linux-watchdog@vger.kernel.org On 05/07/2015 03:09 PM, Doug Anderson wrote: > If you've got code that does this in a tight loop > 1. Open watchdog > 2. Send 'expect close' > 3. Close watchdog > ...you'll eventually trigger a watchdog reset. You can reproduce this > by using daisydog (1) and running: > while true; do daisydog -c > /dev/null; done > > The problem is that each time you write to the watchdog for 'expect > close' it moves the timer .5 seconds out. The timer thus never fires > and never pats the watchdog for you. > > 1: http://git.chromium.org/gitweb/?p=chromiumos/third_party/daisydog.git > > Signed-off-by: Doug Anderson Reviewed-by: Guenter Roeck