From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753294AbcBGCMQ (ORCPT ); Sat, 6 Feb 2016 21:12:16 -0500 Received: from mail-oi0-f45.google.com ([209.85.218.45]:36565 "EHLO mail-oi0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750948AbcBGCMN (ORCPT ); Sat, 6 Feb 2016 21:12:13 -0500 MIME-Version: 1.0 In-Reply-To: <56B6422C.7070302@roeck-us.net> 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> <56B2423B.1020109@codeaurora.org> <56B24642.8090105@codeaurora.org> <56B24AB5.3070001@codeaurora.org> <56B2DEE4.7060901@roeck-us.net> <56B4B4E2.40105@roeck-us.net> <56B5363D.20200@roeck-us.net> <56B6422C.7070302@roeck-us.net> Date: Sun, 7 Feb 2016 10:12:12 +0800 Message-ID: Subject: Re: [PATCH v10 5/5] Watchdog: ARM SBSA Generic Watchdog half timeout panic support From: Fu Wei To: Guenter Roeck Cc: Timur Tabi , Rob Herring , =?UTF-8?Q?Pawe=C5=82_Moll?= , Mark Rutland , Ian Campbell , Kumar Gala , Wim Van Sebroeck , 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 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7 February 2016 at 02:57, Guenter Roeck wrote: > On 02/06/2016 10:02 AM, Fu Wei wrote: >> >> Hi Guenter, >> >> On 6 February 2016 at 07:54, Guenter Roeck wrote: >>> >>> On 02/05/2016 10:21 AM, Fu Wei wrote: >>>> >>>> >>>> On 5 February 2016 at 22:42, Guenter Roeck wrote: >>>>> >>>>> >>>>> On 02/05/2016 01:51 AM, Fu Wei wrote: >>>>>> >>>>>> >>>>>> >>>>>> Hi Guenter, >>>>>> >>>>>> On 4 February 2016 at 13:17, Guenter Roeck wrote: >>>>>>> >>>>>>> >>>>>>> >>>>>>> On 02/03/2016 03:00 PM, Fu Wei wrote: >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> On 4 February 2016 at 02:45, Timur Tabi >>>>>>>> wrote: >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> Fu Wei wrote: >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> As you know I have made the pre-timeout support patch, If people >>>>>>>>>> like >>>>>>>>>> it, i am happy to go on upstream it separately. >>>>>>>>>> >>>>>>>>>> If we want to use pre-timeout here, user only can use >>>>>>>>>> get_pretimeout >>>>>>>>>> and disable panic by setting pretimeout to 0 >>>>>>>>>> but user can not really set pretimeout, because "pre-timeout == >>>>>>>>>> timeout / 2 (always)". >>>>>>>>>> if user want to change pretimeout, he/she has to set_time instead. >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> Ok, I think patches 4 and 5 should be combined, and I think the >>>>>>>>> Kconfig >>>>>>>>> entry should be removed and just use panic_enabled. >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>> >>>>>>> Agreed. >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> np, will do >>>>>> >>>>>>>> >>>>>>>> >>>>>>>> NP, will update this patchset like that , thanks :-) >>>>>>>> >>>>>>> >>>>>>> Also, if panic is enabled, the timeout needs to be adjusted >>>>>>> accordingly >>>>>>> (to only panic after the entire timeout period has expired, not after >>>>>>> half of it). We can not panic the system after timeout / 2. >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> OK, my thought is >>>>>> >>>>>> if panic is enabled : >>>>>> |--------WOR-------WS0--------WOR-------WS1 >>>>>> |------timeout------(panic)------timeout-----reset >>>>>> >>>>>> if panic is disabled . >>>>>> |--------WOR-------WS0--------WOR-------WS1 >>>>>> |---------------------timeout---------------------reset >>>>>> >>>>>> panic_enabled only can be configured when module is loaded by >>>>>> module >>>>>> parameter >>>>>> >>>>>> But user should know that max_timeout(panic_enable) = >>>>>> max_timeout(panic_disable) / 2 >>>>>> >>>>> >>>>> That means you'll have to update max_timeout accordingly. >>>> >>>> >>>> >>>> panic_enabled only can be configured when module is loaded, so we >>>> don't need to update it. >>>> >>>> max_timeout will only be set up in the init stage. >>>> >>>> Does it make sense ? :-) >>>> >>> Not sure I understand your problem or question. >>> >>> max_timeout will have to reflect the correct maximum timeout, under >>> all circumstances. It will have to be set to the correct value before >>> the watchdog driver is registered. >> >> >> yes, understood, my thought is : >> >> in static int sbsa_gwdt_probe(struct platform_device *pdev) >> >> if (action) { >> wdd->min_timeout = 1; >> wdd->max_timeout = U32_MAX / gwdt->clk; >> } else { >> wdd->min_timeout = 2; >> wdd->max_timeout = U32_MAX / gwdt->clk * 2; > > > Pretty much, though you would also have to adjust all calculations > using gwdt->clk, in both set_timeout() and get_timeout(). Wonder if > you could adjust gwdt->clk instead. > > Does min_timeout really have to be 2 if panic is disabled ? > The only reason seems to be the calculation in sbsa_gwdt_set_timeout(). > > writel(timeout / 2 * gwdt->clk, gwdt->control_base + SBSA_GWDT_WOR); > > Maybe you could use something like > > writel(timeout * (gwdt->clk / 2), ...); > > instead. Or, as mentioned above, adjust the value of gwdt->clk > to include the factor. yes, Thanks for pointing it out. I will fix that following your suggestion. > > Thanks, > Guenter > -- 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