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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 F08F6FA3728 for ; Wed, 16 Oct 2019 14:23:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CA5EA21D7B for ; Wed, 16 Oct 2019 14:23:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2392327AbfJPOXr (ORCPT ); Wed, 16 Oct 2019 10:23:47 -0400 Received: from foss.arm.com ([217.140.110.172]:41208 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727451AbfJPOXr (ORCPT ); Wed, 16 Oct 2019 10:23:47 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 8C76A142F; Wed, 16 Oct 2019 07:23:46 -0700 (PDT) Received: from bogus (unknown [10.1.196.42]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 6EBCC3F68E; Wed, 16 Oct 2019 07:23:45 -0700 (PDT) Date: Wed, 16 Oct 2019 15:23:43 +0100 From: Sudeep Holla To: "Rafael J. Wysocki" Cc: Linux PM , Linux ACPI , LKML , Viresh Kumar , Sudeep Holla , Dmitry Osipenko Subject: Re: [RFT][PATCH 0/3] cpufreq / PM: QoS: Introduce frequency QoS and use it in cpufreq Message-ID: <20191016142343.GB5330@bogus> References: <2811202.iOFZ6YHztY@kreacher> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2811202.iOFZ6YHztY@kreacher> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org On Wed, Oct 16, 2019 at 12:37:58PM +0200, Rafael J. Wysocki wrote: > Hi All, > > The motivation for this series is to address the problem discussed here: > > https://lore.kernel.org/linux-pm/5ad2624194baa2f53acc1f1e627eb7684c577a19.1562210705.git.viresh.kumar@linaro.org/T/#md2d89e95906b8c91c15f582146173dce2e86e99f > > and also reported here: > > https://lore.kernel.org/linux-pm/20191015155735.GA29105@bogus/ > > Plus, generally speaking, using the policy CPU as a proxy for the policy > with respect to PM QoS does not feel particularly straightforward to me > and adds extra complexity. > > Anyway, the first patch adds frequency QoS that is based on "raw" PM QoS (kind > of in analogy with device PM QoS) and is just about min and max frequency > requests (no direct relationship to devices). > > The second patch switches over cpufreq and its users to the new frequency QoS. > [The Fixes: tag has been tentatively added to it.] > > The third one removes frequency request types from device PM QoS. > > Unfortunately, the patches are rather big, but also they are quite > straightforward. > > I didn't have the time to test this series, so giving it a go would be much > appreciated. Thanks for the spinning these patches so quickly. I did give it a spin, but unfortunately it doesn't fix the bug I reported. So I looked at my bug report in detail and looks like the cpufreq_driver variable is set to NULL at that point and it fails to dereference it while trying to execute: ret = cpufreq_driver->verify(new_policy); (Hint verify is at offset 0x1c/28) So I suspect some race as this platform with bL switcher tries to unregister and re-register the cpufreq driver during the boot. I need to spend more time on this as reverting the initial PM QoS patch to cpufreq.c makes the issue disappear. -- Regards, Sudeep