From mboxrd@z Thu Jan 1 00:00:00 1970 From: Viresh Kumar Subject: Re: [PATCH][v2] cpufreq: Bring CPUs up even if cpufreq_online failed Date: Tue, 11 Apr 2017 11:41:00 +0530 Message-ID: <20170411061100.GC3670@vireshk-i7> References: <1491716716-22222-1-git-send-email-yu.c.chen@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-pf0-f175.google.com ([209.85.192.175]:36061 "EHLO mail-pf0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752224AbdDKGLD (ORCPT ); Tue, 11 Apr 2017 02:11:03 -0400 Received: by mail-pf0-f175.google.com with SMTP id o126so43941747pfb.3 for ; Mon, 10 Apr 2017 23:11:03 -0700 (PDT) Content-Disposition: inline In-Reply-To: <1491716716-22222-1-git-send-email-yu.c.chen@intel.com> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Chen Yu Cc: "Rafael J. Wysocki" , Sebastian Andrzej Siewior , Len Brown , linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, "Stable # 4 . 9+" On 09-04-17, 13:45, Chen Yu wrote: > There is a report that after > commit 27622b061eb4 ("cpufreq: Convert to hotplug state machine"), > the normal CPU offline/online cycle failed on some platforms. > According to the ftrace result, this problem was triggered on > platforms using acpi-freq as the default cpufreq driver, > and due to the lack of some ACPI freq method(_PCT eg), the > cpufreq_online failed and returned a negative value, thus the CPU > hotplug statemachine rollbacked the CPU online process. Actually > from the user's perspective the failure of cpufreq_online should > not prevent that CPU from being brought up, although cpufreq might > not work on that CPU. BTW, during system bootup the cpufreq_online > is not invoked via cpuhotplug statemachine but by the cpufreq device > creation process, thus the APs can be brought up although cpufreq_online > failed in that stage. > > This patch ignores the return value of cpufreq_online/offline and > let the cpufreq framework to deal with the failure that, cpufreq_online() > will do a proper rollback in that case. And if the _PCT is missing, > the acpi cpufreq driver will print a warning if the corresponding > debug options have been enabled. > > Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=194581 > Fixes: 27622b061eb4 ("cpufreq: Convert to hotplug state machine") > Reported-and-tested-by: Tomasz Maciej Nowak > Cc: "Rafael J. Wysocki" > Cc: Viresh Kumar > Cc: Sebastian Andrzej Siewior > Cc: Len Brown > Cc: linux-pm@vger.kernel.org > Cc: linux-kernel@vger.kernel.org > Cc: Stable # 4.9+ > Signed-off-by: Chen Yu > --- > v2: > - According to Rafael and Sebastian's suggestion, remove > the error log in cpuhp_cpufreq_online/offline, and let > the cpufreq_online and cpufreq_offline to print the warning > and do the necessary rollback if they failed. > --- > drivers/cpufreq/cpufreq.c | 18 ++++++++++++++++-- > 1 file changed, 16 insertions(+), 2 deletions(-) > > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c > index bc96d42..0e3f649 100644 > --- a/drivers/cpufreq/cpufreq.c > +++ b/drivers/cpufreq/cpufreq.c > @@ -2398,6 +2398,20 @@ EXPORT_SYMBOL_GPL(cpufreq_boost_enabled); > *********************************************************************/ > static enum cpuhp_state hp_online; > > +static int cpuhp_cpufreq_online(unsigned int cpu) > +{ > + cpufreq_online(cpu); > + > + return 0; > +} > + > +static int cpuhp_cpufreq_offline(unsigned int cpu) > +{ > + cpufreq_offline(cpu); > + > + return 0; > +} > + > /** > * cpufreq_register_driver - register a CPU Frequency driver > * @driver_data: A struct cpufreq_driver containing the values# > @@ -2460,8 +2474,8 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data) > } > > ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "cpufreq:online", > - cpufreq_online, > - cpufreq_offline); > + cpuhp_cpufreq_online, > + cpuhp_cpufreq_offline); > if (ret < 0) > goto err_if_unreg; > hp_online = ret; Acked-by: Viresh Kumar -- viresh