From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753698AbeBBTe4 (ORCPT ); Fri, 2 Feb 2018 14:34:56 -0500 Received: from smtp.codeaurora.org ([198.145.29.96]:58560 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753109AbeBBTer (ORCPT ); Fri, 2 Feb 2018 14:34:47 -0500 DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org C6E1B6050D Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=skannan@codeaurora.org Message-ID: <5A74BD55.5000402@codeaurora.org> Date: Fri, 02 Feb 2018 11:34:45 -0800 From: Saravana Kannan User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130329 Thunderbird/17.0.5 MIME-Version: 1.0 To: "Rafael J. Wysocki" CC: Bo Yan , viresh.kumar@linaro.org, sgurrappadi@nvidia.com, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] cpufreq: skip cpufreq resume if it's not suspended References: <1516744675-21233-1-git-send-email-byan@nvidia.com> <1744712.rO4QOLozun@aspire.rjw.lan> <913f1715-bdd0-1c03-ad76-38be9d3d2298@nvidia.com> <17447147.z6jfkRxuEB@aspire.rjw.lan> In-Reply-To: <17447147.z6jfkRxuEB@aspire.rjw.lan> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/02/2018 03:54 AM, Rafael J. Wysocki wrote: > On Wednesday, January 24, 2018 9:53:14 PM CET Bo Yan wrote: >> >> On 01/23/2018 06:02 PM, Rafael J. Wysocki wrote: >>> On Tuesday, January 23, 2018 10:57:55 PM CET Bo Yan wrote: >>>> drivers/cpufreq/cpufreq.c | 4 ++++ >>>> 1 file changed, 4 insertions(+) >>>> >>>> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c >>>> index 41d148af7748..95b1c4afe14e 100644 >>>> --- a/drivers/cpufreq/cpufreq.c >>>> +++ b/drivers/cpufreq/cpufreq.c >>>> @@ -1680,6 +1680,10 @@ void cpufreq_resume(void) >>>> if (!cpufreq_driver) >>>> return; >>>> >>>> + if (unlikely(!cpufreq_suspended)) { >>>> + pr_warn("%s: resume after failing suspend\n", __func__); >>>> + return; >>>> + } >>>> cpufreq_suspended = false; >>>> >>>> if (!has_target() && !cpufreq_driver->resume) >>>> >>> Good catch, but rather than doing this it would be better to avoid >>> calling cpufreq_resume() at all if cpufreq_suspend() has not been called. >> Yes, I thought about that, but there is no good way to skip over it >> without introducing another flag. cpufreq_resume is called by >> dpm_resume, cpufreq_suspend is called by dpm_suspend. In the failure >> case, dpm_resume is called, but dpm_suspend is not. So on a higher level >> it's already unbalanced. >> >> One possibility is to rely on the pm_transition flag. So something like: >> >> >> diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c >> index dc259d20c967..8469e6fc2b2c 100644 >> --- a/drivers/base/power/main.c >> +++ b/drivers/base/power/main.c >> @@ -842,6 +842,7 @@ static void async_resume(void *data, async_cookie_t >> cookie) >> void dpm_resume(pm_message_t state) >> { >> struct device *dev; >> + bool suspended = (pm_transition.event != PM_EVENT_ON); >> ktime_t starttime = ktime_get(); >> >> trace_suspend_resume(TPS("dpm_resume"), state.event, true); >> @@ -885,7 +886,8 @@ void dpm_resume(pm_message_t state) >> async_synchronize_full(); >> dpm_show_time(starttime, state, NULL); >> >> - cpufreq_resume(); >> + if (likely(suspended)) >> + cpufreq_resume(); >> trace_suspend_resume(TPS("dpm_resume"), state.event, false); >> } > > I was thinking about something else. > > Anyway, I think your original patch is OK too, but without printing the > message. Just combine the cpufreq_suspended check with the cpufreq_driver > one and the unlikely() thing is not necessary. > I rather have this fixed in the dpm_suspend/resume() code. This is just masking the first issue that's being caused by unbalanced error handling. If that means adding flags in dpm_suspend/resume() then that's what we should do right now and clean it up later if it can be improved. Making cpufreq more messy doesn't seem like the right answer. Thanks, Saravana -- Qualcomm Innovation Center, Inc. The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project