From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from bh-25.webhostbox.net ([208.91.199.152]:33018 "EHLO bh-25.webhostbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758100AbcDESr0 (ORCPT ); Tue, 5 Apr 2016 14:47:26 -0400 Date: Tue, 5 Apr 2016 11:47:27 -0700 From: Guenter Roeck To: "fixed-term.Oleksij.Rempel" Cc: Wolfram Sang , Oleksij Rempel , dirk.behme@de.bosch.com, linux-watchdog@vger.kernel.org Subject: Re: [PATCH v2 1/4] watchdog: renesas-wdt: add driver Message-ID: <20160405184727.GA5862@roeck-us.net> References: <1459511786-4286-1-git-send-email-wsa@the-dreams.de> <1459511786-4286-2-git-send-email-wsa@the-dreams.de> <57010C13.7040007@rempel-privat.de> <20160404104508.GA1383@katana> <57025C5A.2060704@de.bosch.com> <20160404123654.GA2983@katana> <20160404140812.GB10556@roeck-us.net> <57035A6A.3020601@de.bosch.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <57035A6A.3020601@de.bosch.com> Sender: linux-watchdog-owner@vger.kernel.org List-Id: linux-watchdog@vger.kernel.org On Tue, Apr 05, 2016 at 08:25:46AM +0200, fixed-term.Oleksij.Rempel wrote: > > > On 04.04.2016 16:08, Guenter Roeck wrote: > > On Mon, Apr 04, 2016 at 02:36:54PM +0200, Wolfram Sang wrote: > >> > >>> we are using it. So it should be implemented in this driver as well, > >>> if it is not supported by HW, then we will need to use second timer or > >>> watchdog for pretimeout interrupt. > >> > >> As I said, I have no task like this assigned (and no personal interest, > >> too). So, you'd need to do it yourself, hire me, or request this feature > >> from Renesas (and hope that they pass the task to me ;)). > >> > > Sorry, I lost the context here. > > > >>> Please correct me if i'm wrong - module parameter is a way to ignore > >>> kernel config. For same purpose, to disable wdt at runtime "magic 'V'" > >>> should be used. > >> > >> I have to admit that I don't have a specific use-case, I just did > >> general support as requested. So, I followed the style that basically > >> every other watchdog driver has this parameter. > >> > > I don't understand this one. Unless I am missing something, the module > > parameter is standard, and magic close by writing 'V' is supported. > > What is the problem ? > > Sorry it was more about our internal requirements, which are fallowing: > - WDT is always on. there should be no option to disable it. > - WDTs can fail, it is proven fact. In our case, worst scenario, failed > WDT will kill a car battery. This is why we use many watchdogs in one > system. So, using differently configured WDTs of one SoC is valid use > case. From this point, module options are kind of sweet but useless or > harmful. No one _has_ to use the module parameter. That doesn't mean that it must not be there - someone else may want it for some reason. > - pretimout interrupt is not optional - not any more. Some issues are > wary hard or impossible to reproduce. Pretimout interrupt helped us to > debug some of them. If WDT hardware can't provide one, we will need to > mix two watchdogs (one for reset and other for interrupt) or wdt with > some other hw timer. Adding pretimeout support should be easy with a follow-up patch. > > May be this requirements can be passed to upstream as well :) Keep in mind that a specific use case does not and should not mandate driver implementation details. The driver can support both module parameter and pretimeout, but none of those has to be used in a specific application. Important is that the kernel _supports_ your use case, which should be no problem. Thanks, Guenter