From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756063Ab1KXNqI (ORCPT ); Thu, 24 Nov 2011 08:46:08 -0500 Received: from mailrelay007.isp.belgacom.be ([195.238.6.173]:39369 "EHLO mailrelay007.isp.belgacom.be" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755202Ab1KXNqF (ORCPT ); Thu, 24 Nov 2011 08:46:05 -0500 X-Belgacom-Dynamic: yes X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: Av0EAGtJzk5tg6zW/2dsb2JhbAA7CKpxgQaBcgEBBAE6HCMFCwgDRhQlAyGIGAK0eRKHH4MxBJRJkg0 Date: Thu, 24 Nov 2011 14:42:47 +0100 From: Wim Van Sebroeck To: Marc Vertes Cc: w.sang@pengutronix.de, linux-watchdog@vger.kernel.org, linux-kernel@vger.kernel.org, HaraldWelte@viatech.com, broonie@opensource.wolfsonmicro.com Subject: Re: [PATCH RFC] watchdog: add a new driver for VIA chipsets Message-ID: <20111124134247.GS23376@infomag.iguana.be> References: <20111122173227.GK6624@sirena.org.uk> <20111122184051.GA30941@pengutronix.de> <4eccc3f0.iApQ//mCzaN3UsrB%marc.vertes@sigfox.com> <20111123104926.GB4063@pengutronix.de> <20111123121329.GM23376@infomag.iguana.be> <20111123122018.GA12227@opensource.wolfsonmicro.com> <20111123124037.GN23376@infomag.iguana.be> <4ecd075d.2YyTTCA13zxwZmwT%marc.vertes@sigfox.com> <20111123214614.GQ23376@infomag.iguana.be> <4ece231e./LkW+9i4Wmz+9zzn%marc.vertes@sigfox.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4ece231e./LkW+9i4Wmz+9zzn%marc.vertes@sigfox.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Marc, > I have tested your version and it works fine. I saw that you enforced > the NO_WAY_OUT bit and implemented the KEEPALIVEPING and MAGICCLOSE > features properly. Many thanks. No problem. > Regarding the timer, the driver can not read the timeout value set in > the BIOS, so there is still a risk of reboot if the BIOS value is lower > than driver one. I assume that other drivers may be in the same case, > and that is required for user compatibility anyway. The driver assumes 1 second as heartbeat of the watchdog device. It thus takes half of this time do actually 'tickle' the watchdog. (or 500ms). We should set this 1 second value to the smallest time that is possible (either the smallest value that can be set in the BIOS or the smallest value that is listed in the datasheets). > Here is the comment block that I propose to insert regarding register > programming issues: > > /* > * Caveat: the only known way to activate the watchdog timer or to set > * its period is through BIOS configuration, when the hardware supports it. > * It seems that the watchdog control registers are locked and disabled if > * the watchdog is not exposed or enabled by BIOS, and that writing them is > * useless. No public documentation is available regarding this limitation. > */ Looks good. I will add this. Just let me know what the smallest value is for the timeout in the BIOS and/or datasheet and I will do the necessary for inclusion in the watchdog tree. Kind regards, Wim.