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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 0736DC76195 for ; Tue, 16 Jul 2019 09:21:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DDFCE217D9 for ; Tue, 16 Jul 2019 09:21:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727105AbfGPJVi (ORCPT ); Tue, 16 Jul 2019 05:21:38 -0400 Received: from mga04.intel.com ([192.55.52.120]:50341 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727849AbfGPJVh (ORCPT ); Tue, 16 Jul 2019 05:21:37 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga006.jf.intel.com ([10.7.209.51]) by fmsmga104.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 16 Jul 2019 02:21:37 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.63,497,1557212400"; d="scan'208";a="172490148" Received: from rjwysock-mobl1.ger.corp.intel.com (HELO [10.249.128.254]) ([10.249.128.254]) by orsmga006.jf.intel.com with ESMTP; 16 Jul 2019 02:21:35 -0700 Subject: Re: [PATCH AUTOSEL 4.19 123/158] cpufreq: Don't skip frequency validation for has_target() drivers To: Sasha Levin , linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Viresh Kumar , linux-pm@vger.kernel.org References: <20190715141809.8445-1-sashal@kernel.org> <20190715141809.8445-123-sashal@kernel.org> From: "Rafael J. Wysocki" Organization: Intel Technology Poland Sp. z o. o., KRS 101882, ul. Slowackiego 173, 80-298 Gdansk Message-ID: <92ae669e-654c-40b2-0470-e9280d9c2dd0@intel.com> Date: Tue, 16 Jul 2019 11:21:34 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: <20190715141809.8445-123-sashal@kernel.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org On 7/15/2019 4:17 PM, Sasha Levin wrote: > From: Viresh Kumar > > [ Upstream commit 9801522840cc1073f8064b4c979b7b6995c74bca ] > > CPUFREQ_CONST_LOOPS was introduced in a very old commit from pre-2.6 > kernel release by commit 6a4a93f9c0d5 ("[CPUFREQ] Fix 'out of sync' > issue"). > > Basically, that commit does two things: > > - It adds the frequency verification code (which is quite similar to > what we have today as well). > > - And it sets the CPUFREQ_CONST_LOOPS flag only for setpolicy drivers, > rightly so based on the code we had then. The idea was to avoid > frequency validation for setpolicy drivers as the cpufreq core doesn't > know what frequency the hardware is running at and so no point in > doing frequency verification. > > The problem happened when we started to use the same CPUFREQ_CONST_LOOPS > flag for constant loops-per-jiffy thing as well and many has_target() > drivers started using the same flag and unknowingly skipped the > verification of frequency. There is no logical reason behind skipping > frequency validation because of the presence of CPUFREQ_CONST_LOOPS > flag otherwise. > > Fix this issue by skipping frequency validation only for setpolicy > drivers and always doing it for has_target() drivers irrespective of > the presence or absence of CPUFREQ_CONST_LOOPS flag. > > cpufreq_notify_transition() is only called for has_target() type driver > and not for set_policy type, and the check is simply redundant. Remove > it as well. > > Also remove () around freq comparison statement as they aren't required > and checkpatch also warns for them. > > Signed-off-by: Viresh Kumar > Signed-off-by: Rafael J. Wysocki > Signed-off-by: Sasha Levin > --- > drivers/cpufreq/cpufreq.c | 13 +++++-------- > 1 file changed, 5 insertions(+), 8 deletions(-) > > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c > index d3213594d1a7..80942ec34efd 100644 > --- a/drivers/cpufreq/cpufreq.c > +++ b/drivers/cpufreq/cpufreq.c > @@ -321,12 +321,10 @@ static void cpufreq_notify_transition(struct cpufreq_policy *policy, > * which is not equal to what the cpufreq core thinks is > * "old frequency". > */ > - if (!(cpufreq_driver->flags & CPUFREQ_CONST_LOOPS)) { > - if (policy->cur && (policy->cur != freqs->old)) { > - pr_debug("Warning: CPU frequency is %u, cpufreq assumed %u kHz\n", > - freqs->old, policy->cur); > - freqs->old = policy->cur; > - } > + if (policy->cur && policy->cur != freqs->old) { > + pr_debug("Warning: CPU frequency is %u, cpufreq assumed %u kHz\n", > + freqs->old, policy->cur); > + freqs->old = policy->cur; > } > > for_each_cpu(freqs->cpu, policy->cpus) { > @@ -1543,8 +1541,7 @@ static unsigned int __cpufreq_get(struct cpufreq_policy *policy) > if (policy->fast_switch_enabled) > return ret_freq; > > - if (ret_freq && policy->cur && > - !(cpufreq_driver->flags & CPUFREQ_CONST_LOOPS)) { > + if (has_target() && ret_freq && policy->cur) { > /* verify no discrepancy between actual and > saved value exists */ > if (unlikely(ret_freq != policy->cur)) { This is not -stable material, please drop it.