From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965568AbcBCSGK (ORCPT ); Wed, 3 Feb 2016 13:06:10 -0500 Received: from mail-ob0-f171.google.com ([209.85.214.171]:35743 "EHLO mail-ob0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965175AbcBCSGD (ORCPT ); Wed, 3 Feb 2016 13:06:03 -0500 MIME-Version: 1.0 In-Reply-To: <56B23E99.1030604@codeaurora.org> References: <1454519923-25230-1-git-send-email-fu.wei@linaro.org> <1454519923-25230-6-git-send-email-fu.wei@linaro.org> <56B23883.7000501@codeaurora.org> <56B23E99.1030604@codeaurora.org> Date: Thu, 4 Feb 2016 02:06:02 +0800 Message-ID: Subject: Re: [PATCH v10 5/5] Watchdog: ARM SBSA Generic Watchdog half timeout panic support From: Fu Wei To: Timur Tabi Cc: Rob Herring , =?UTF-8?Q?Pawe=C5=82_Moll?= , Mark Rutland , Ian Campbell , Kumar Gala , Wim Van Sebroeck , Guenter Roeck , Jon Corbet , Catalin Marinas , Will Deacon , Suravee Suthikulpanit , LKML , linux-watchdog@vger.kernel.org, linux-doc@vger.kernel.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Linaro ACPI Mailman List , rruigrok@codeaurora.org, "Abdulhamid, Harb" , Christopher Covington , Dave Young , Pratyush Anand , G Gregory , Al Stone , Hanjun Guo , Jon Masters , Arnd Bergmann , Leo Duran , sudeep.holla@arm.com Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Timur On 4 February 2016 at 01:53, Timur Tabi wrote: > Fu Wei wrote: >> >> sorry, are you saying : using pre-timeout instead of this half timeout? >> >> But even we have pre-timeout support, pre-timeout == timeout / 2, it >> can not be configured without touch timeout. >> >> if you want pre-timeout != timeout / 2, we have to modify WCV in the >> interrupt routine. >> (because of the explicit watchdog refresh mechanism) >> >> Could you let me know why we need pre-timeout here ??:-) > > > What I meant was that if we had full-blown pre-timeout support in the > watchdog layer, then you could use that to implement the > panic-on-half-timeout feature. > > When pre-timeout is implemented, will you modify the interrupt handler to > use it? Sorry I am little confused. Actually I am taking your suggestion to avoid touching WCV in interrupt routine. So even we have pre-timeout support , it is useless for this panic-on-half-timeout feature, because pre-timeout == timeout / 2 (always). So maybe I misunderstand your suggestion, could you let me know : why we want pre-timeout here? > >>> >belong upstream. But like I said, it's just my opinion, and I won't >>> >complain if I'm outvoted. >> >> I think this debugging feature is the purpose of the two-stage >> watchdog, if I understand correctly > > > Hmmm... that make sense. I think maybe you should drop the Kconfig option, > and just have "static bool panic_enabled = false;" Also, then do this: > > if (panic_enabled) { > ret = devm_request_irq(dev, irq, sbsa_gwdt_interrupt, 0, > pdev->name, gwdt); > if (ret) { > dev_err(dev, "unable to request IRQ %d\n", irq); > return ret; > } > } yes, agree > > That way, the interrupt handler is never registered if the command-line > parameter is not specified. > -- Best regards, Fu Wei Software Engineer Red Hat Software (Beijing) Co.,Ltd.Shanghai Branch Ph: +86 21 61221326(direct) Ph: +86 186 2020 4684 (mobile) Room 1512, Regus One Corporate Avenue,Level 15, One Corporate Avenue,222 Hubin Road,Huangpu District, Shanghai,China 200021