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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D2E76EB64DB for ; Thu, 22 Jun 2023 07:47:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229954AbjFVHrU (ORCPT ); Thu, 22 Jun 2023 03:47:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49098 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229903AbjFVHrT (ORCPT ); Thu, 22 Jun 2023 03:47:19 -0400 Received: from wp530.webpack.hosteurope.de (wp530.webpack.hosteurope.de [80.237.130.52]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 664591A1; Thu, 22 Jun 2023 00:47:18 -0700 (PDT) Received: from [2a02:8108:8980:2478:8cde:aa2c:f324:937e]; authenticated by wp530.webpack.hosteurope.de running ExIM with esmtpsa (TLS1.3:ECDHE_RSA_AES_128_GCM_SHA256:128) id 1qCF2B-0007GM-LL; Thu, 22 Jun 2023 09:47:15 +0200 Message-ID: <5240ce3f-37fa-2747-92ee-23d71619f3ef@leemhuis.info> Date: Thu, 22 Jun 2023 09:47:14 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.12.0 Subject: Re: [PATCH] arm64: dts: qcom: sdm845-db845c: Move LVS regulator nodes up Content-Language: en-US, de-DE To: Bjorn Andersson , Doug Anderson Cc: Krzysztof Kozlowski , Linux regressions mailing list , Amit Pundir , Mark Brown , Andy Gross , Rob Herring , Konrad Dybcio , Krzysztof Kozlowski , Caleb Connolly , Conor Dooley , linux-arm-msm , dt , lkml References: <20230602161246.1855448-1-amit.pundir@linaro.org> <358c69ad-fa8a-7386-fe75-92369883ee48@leemhuis.info> <0f6c9dcb-b7f6-fff9-6bed-f4585ea8e487@linaro.org> <20230620155902.clspxncyvpodixft@ripper> From: "Linux regression tracking (Thorsten Leemhuis)" Reply-To: Linux regressions mailing list In-Reply-To: <20230620155902.clspxncyvpodixft@ripper> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-bounce-key: webpack.hosteurope.de;regressions@leemhuis.info;1687420038;6ef2419a; X-HE-SMSGID: 1qCF2B-0007GM-LL Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org Hi, Thorsten here, the Linux kernel's regression tracker. Top-posting for once, to make this easily accessible to everyone. As Linus will likely release 6.4 on this or the following Sunday a quick status inquiry so I can brief him appropriately: is there any hope the regression this patch tried to fix will be resolved any time soon? Doesn't look like it from below message and this thread, but maybe I missed something. Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat) -- Everything you wanna know about Linux kernel regression tracking: https://linux-regtracking.leemhuis.info/about/#tldr If I did something stupid, please tell me, as explained on that page. #regzbot poke On 20.06.23 17:59, Bjorn Andersson wrote: > On Wed, Jun 14, 2023 at 12:44:15PM -0700, Doug Anderson wrote: >> Hi, >> >> On Wed, Jun 14, 2023 at 11:47 AM Krzysztof Kozlowski >> wrote: >>> >>> On 14/06/2023 20:18, Linux regression tracking (Thorsten Leemhuis) wrote: >>>> On 02.06.23 18:12, Amit Pundir wrote: >>>>> Move lvs1 and lvs2 regulator nodes up in the rpmh-regulators >>>>> list to workaround a boot regression uncovered by the upstream >>>>> commit ad44ac082fdf ("regulator: qcom-rpmh: Revert "regulator: >>>>> qcom-rpmh: Use PROBE_FORCE_SYNCHRONOUS""). >>>>> >>>>> Without this fix DB845c fail to boot at times because one of the >>>>> lvs1 or lvs2 regulators fail to turn ON in time. >>>> >>>> /me waves friendly >>>> >>>> FWIW, as it's not obvious: this... >>>> >>>>> Link: https://lore.kernel.org/all/CAMi1Hd1avQDcDQf137m2auz2znov4XL8YGrLZsw5edb-NtRJRw@mail.gmail.com/ >>>> >>>> ...is a report about a regression. One that we could still solve before >>>> 6.4 is out. One I'll likely will point Linus to, unless a fix comes into >>>> sight. >>>> >>>> When I noticed the reluctant replies to this patch I earlier today asked >>>> in the thread with the report what the plan forward was: >>>> https://lore.kernel.org/all/CAD%3DFV%3DV-h4EUKHCM9UivsFHRsJPY5sAiwXV3a1hUX9DUMkkxdg@mail.gmail.com/ >>>> >>>> Dough there replied: >>>> >>>> ``` >>>> Of the two proposals made (the revert vs. the reordering of the dts), >>>> the reordering of the dts seems better. It only affects the one buggy >>>> board (rather than preventing us to move to async probe for everyone) >>>> and it also has a chance of actually fixing something (changing the >>>> order that regulators probe in rpmh-regulator might legitimately work >>>> around the problem). That being said, just like the revert the dts >>>> reordering is still just papering over the problem and is fragile / >>>> not guaranteed to work forever. >>>> ``` >>>> >>>> Papering over obviously is not good, but has anyone a better idea to fix >>>> this? Or is "not fixing" for some reason an viable option here? >>>> >>> >>> I understand there is a regression, although kernel is not mainline >>> (hash df7443a96851 is unknown) and the only solutions were papering the >>> problem. Reverting commit is a temporary workaround. Moving nodes in DTS >>> is not acceptable because it hides actual problem and only solves this >>> one particular observed problem, while actual issue is still there. It >>> would be nice to be able to reproduce it on real mainline with normal >>> operating system (not AOSP) - with ramdiks/without/whatever. So far no >>> one did it, right? >> >> The worry I have about the revert here is that it will never be able >> to be undone and that doesn't seem great long term. I'm all for a >> temporary revert to fix a problem while the root cause is understood, >> but in this case I have a hard time believing that we'll make more >> progress towards a root cause once the revert lands. All the >> investigation we've done so far seems to indicate that the revert only >> fixes the problem by luck... >> >> I completely agree that moving the nodes in the DTS is a hack and just >> hides the problem. However, it also at least limits the workaround to >> the one board showing the problem and doesn't mean we're stuck with >> synchronous probe for rpmh-regulator for all eternity because nobody >> can understand this timing issue on db845c. >> > > I agree that we shouldn't hide this by reverting the regulator change. > > > And as has been stated a few times already, the symptom indicates that > we have a misconfigured system. > > Before accepting a patch just shuffling the bricks, I'd like to see some > more analysis of what happens wrt the rpmh right before the timeout. > Perhaps the landing team can assist here? > > Regards, > Bjorn > >