From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752608AbZH0U1L (ORCPT ); Thu, 27 Aug 2009 16:27:11 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752566AbZH0U1J (ORCPT ); Thu, 27 Aug 2009 16:27:09 -0400 Received: from mailrelay004.isp.belgacom.be ([195.238.6.170]:29782 "EHLO mailrelay004.isp.belgacom.be" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752427AbZH0U1I (ORCPT ); Thu, 27 Aug 2009 16:27:08 -0400 X-Belgacom-Dynamic: yes X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: ApoEAASIlkpR92Cn/2dsb2JhbADYbAmEEAU Date: Thu, 27 Aug 2009 22:27:09 +0200 From: Wim Van Sebroeck To: Josh Boyer Cc: Chris Friesen , linuxppc-dev@ozlabs.org, Linux kernel Subject: Re: [PATCH] fix book E watchdog to take WDIOC_SETTIMEOUT arg in seconds Message-ID: <20090827202709.GK29382@infomag.iguana.be> References: <4A8303C6.7070705@nortel.com> <20090827111458.GB29382@infomag.iguana.be> <20090827120841.GA25303@zod.rchland.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090827120841.GA25303@zod.rchland.ibm.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 Josh, > >Now we only need someone that can look at the CONFIG_4xx cases still :-) > > It seems the FSL watchdog is much more flexible than the one found in 4xx > cores. On 4xx, you basically have 4 static choices that represent specific > times determined by the clock frequency. I'm concerned that the lack of > granularity here will result in less than desirable behavior. > > For example, with a 400MHz clock you would get choices of roughly: > > 5.2 ms > 83.9 ms > 1.34 s > 21.47 s > > Personally, I consider the first two options basically unusable. Considering > the second two, if a user were to say "Set the timeout for 2 seconds" they > would then get a timeout of 21 seconds with the framework Chris' patch has > set up. That doesn't really seem to be ideal to me. Hmm, my opinion: in that case we should use a timer that triggers the watchdog until userspaces times out (like we do for other watchdogs allready). Maybe we should split this driver. I have the same issue with the Freescale i.mx driver that is under review also. Kind regards, Wim.