From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 54657C47084 for ; Mon, 24 May 2021 02:38:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2A80061139 for ; Mon, 24 May 2021 02:38:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232209AbhEXCkV (ORCPT ); Sun, 23 May 2021 22:40:21 -0400 Received: from so254-9.mailgun.net ([198.61.254.9]:47957 "EHLO so254-9.mailgun.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231867AbhEXCkT (ORCPT ); Sun, 23 May 2021 22:40:19 -0400 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1621823932; h=Message-ID: References: In-Reply-To: Subject: Cc: To: From: Date: Content-Transfer-Encoding: Content-Type: MIME-Version: Sender; bh=SHZ5ZXlQ2XAJJVf50lE0WJ4HIJjhPbLN965o60VkVL0=; b=X9fKZwX7yX1VzUyw78vLgj+M9Y464snOxN5Gw1/4Zs+MCajDxjs1TDvWAKGdtmzpY6nk1TLz oAh9OG50EcdOY3juFbE1EJDh8/3l660/d38E5+0NNCA7qH0ljazrhKCLPtSg1XbdSGzzDE8o /hGt2/7gCWU09qvisrXAvuzvMIw= X-Mailgun-Sending-Ip: 198.61.254.9 X-Mailgun-Sid: WyI0MWYwYSIsICJsaW51eC1rZXJuZWxAdmdlci5rZXJuZWwub3JnIiwgImJlOWU0YSJd Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by smtp-out-n04.prod.us-west-2.postgun.com with SMTP id 60ab11b27b5af81b5c872740 (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Mon, 24 May 2021 02:38:42 GMT Sender: saiprakash.ranjan=codeaurora.org@mg.codeaurora.org Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 2CC8BC433F1; Mon, 24 May 2021 02:38:42 +0000 (UTC) Received: from mail.codeaurora.org (localhost.localdomain [127.0.0.1]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) (Authenticated sender: saiprakash.ranjan) by smtp.codeaurora.org (Postfix) with ESMTPSA id 774F7C4338A; Mon, 24 May 2021 02:38:39 +0000 (UTC) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Mon, 24 May 2021 08:08:39 +0530 From: Sai Prakash Ranjan To: Guenter Roeck Cc: Andy Gross , Bjorn Andersson , Douglas Anderson , Wim Van Sebroeck , linux-watchdog@vger.kernel.org, Stephen Boyd , Matthias Kaehlcke , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, Guenter Roeck Subject: Re: [PATCH] watchdog: qcom: Move suspend/resume to suspend_late/resume_early In-Reply-To: <948130ae3a0781eb19b7431059852c23@codeaurora.org> References: <20210310202004.1436-1-saiprakash.ranjan@codeaurora.org> <20210310202327.GA237124@roeck-us.net> <948130ae3a0781eb19b7431059852c23@codeaurora.org> Message-ID: <7bbfb6af534c22cd1e50f16aadd412c1@codeaurora.org> X-Sender: saiprakash.ranjan@codeaurora.org User-Agent: Roundcube Webmail/1.3.9 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021-04-20 11:13, Sai Prakash Ranjan wrote: > Hi Guenter, > > On 2021-03-11 01:53, Guenter Roeck wrote: >> On Thu, Mar 11, 2021 at 01:50:04AM +0530, Sai Prakash Ranjan wrote: >>> During suspend/resume usecases and tests, it is common to see issues >>> such as lockups either in suspend path or resume path because of the >>> bugs in the corresponding device driver pm handling code. In such >>> cases, >>> it is important that watchdog is active to make sure that we either >>> receive a watchdog pretimeout notification or a bite causing reset >>> instead of a hang causing us to hard reset the machine. >>> >>> There are good reasons as to why we need this because: >>> >>> * We can have a watchdog pretimeout governor set to panic in which >>> case we can have a backtrace which would help identify the issue >>> with the particular driver and cause a normal reboot. >>> >>> * Even in case where there is no pretimeout support, a watchdog >>> bite is still useful because some firmware has debug support to >>> dump >>> CPU core context on watchdog bite for post-mortem analysis. >>> >>> * One more usecase which comes to mind is of warm reboot. In case we >>> hard reset the target, a cold reboot could be induced resulting in >>> lose of ddr contents thereby losing all the debug info. >>> >>> Currently, the watchdog pm callback just invokes the usual suspend >>> and resume callback which do not have any special ordering in the >>> sense that a watchdog can be suspended before the buggy device driver >>> suspend callback and watchdog resume can happen after the buggy >>> device >>> driver resume callback. This would mean that the watchdog will not be >>> active when the buggy driver cause the lockups thereby hanging the >>> system. So to make sure this doesn't happen, move the watchdog pm to >>> use late/early system pm callbacks which will ensure that the >>> watchdog >>> is suspended late and resumed early so that it can catch such issues. >>> >>> Signed-off-by: Sai Prakash Ranjan >> >> Reviewed-by: Guenter Roeck >> > > Gentle Ping. I don't see this in linux-next or linux-watchdog, please > let > me know if anything is pending from my side. > Gentle Ping !! Thanks, Sai -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation