From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756379Ab1KXOmW (ORCPT ); Thu, 24 Nov 2011 09:42:22 -0500 Received: from 6.mo2.mail-out.ovh.net ([87.98.165.38]:34041 "EHLO mo2.mail-out.ovh.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753694Ab1KXOmV (ORCPT ); Thu, 24 Nov 2011 09:42:21 -0500 X-Greylist: delayed 164176 seconds by postgrey-1.27 at vger.kernel.org; Thu, 24 Nov 2011 09:42:20 EST Date: Thu, 24 Nov 2011 15:42:17 +0100 From: Marc Vertes To: wim@iguana.be Cc: w.sang@pengutronix.de, linux-watchdog@vger.kernel.org, linux-kernel@vger.kernel.org, HaraldWelte@viatech.com, broonie@opensource.wolfsonmicro.com X-Ovh-Mailout: 178.32.228.2 (mo2.mail-out.ovh.net) Subject: Re: [PATCH RFC] watchdog: add a new driver for VIA chipsets Message-ID: <4ece57c9.2i1u841q3U3s+xD7%marc.vertes@sigfox.com> 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> <20111124134247.GS23376@infomag.iguana.be> In-Reply-To: <20111124134247.GS23376@infomag.iguana.be> User-Agent: Heirloom mailx 12.4 7/29/08 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Ovh-Tracer-Id: 6325587152498116399 X-Ovh-Remote: 92.103.90.130 () X-Ovh-Local: 213.186.33.20 (ns0.ovh.net) X-OVH-SPAMSTATE: OK X-OVH-SPAMSCORE: 0 X-OVH-SPAMCAUSE: gggruggvucftvghtrhhoucdtuddrfeefiedrtdekucetggdotefuucfrrhhofhhilhgvmecuqfggjfenuceurghilhhouhhtmecufedttdenucenucfjughrpeffhffvuffkfhgjfgggtgfgsehtjeertddtredvnecuhfhrohhmpeforghrtgcugggvrhhtvghsuceomhgrrhgtrdhvvghrthgvshesshhighhfohigrdgtohhmqeenucffohhmrghinhepne X-Spam-Check: DONE|U 0.5/N X-VR-SPAMSTATE: OK X-VR-SPAMSCORE: -100 X-VR-SPAMCAUSE: gggruggvucftvghtrhhoucdtuddrfeefhedrudehucetggdotefuucfrrhhofhhilhgvmecuqfggjfenuceurghilhhouhhtmecufedttdenucculddquddttddm Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Wim Van Sebroeck wrote: > > 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). > The smallest possible value is 1 second, both in BIOS and datasheet. For info, the maximum value is 1023 seconds, approx. 17 min. I think it is dangerous to set the timer to 1s, both in BIOS, obviously as the boot is still in progress when it expires, and even in the driver, where you loose a chance to avoid mandatory reboot after only 1 second of latency, even if the hardware timer is higher. The value you have set, 15 seconds, is reasonable to me, and should not be lowered. If the BIOS was well designed, it should also not allow less than, say 1 minute. Kind regards, -- Marc