From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758691AbbGHPJh (ORCPT ); Wed, 8 Jul 2015 11:09:37 -0400 Received: from mail-pd0-f177.google.com ([209.85.192.177]:33880 "EHLO mail-pd0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758622AbbGHPJd convert rfc822-to-8bit (ORCPT ); Wed, 8 Jul 2015 11:09:33 -0400 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8BIT To: Morten Rasmussen , peterz@infradead.org, mingo@redhat.com From: Michael Turquette In-Reply-To: <1436293469-25707-38-git-send-email-morten.rasmussen@arm.com> Cc: vincent.guittot@linaro.org, daniel.lezcano@linaro.org, "Dietmar Eggemann" , yuyang.du@intel.com, rjw@rjwysocki.net, "Juri Lelli" , sgurrappadi@nvidia.com, pang.xunlei@zte.com.cn, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, "Rafael J. Wysocki" , "Viresh Kumar" References: <1436293469-25707-1-git-send-email-morten.rasmussen@arm.com> <1436293469-25707-38-git-send-email-morten.rasmussen@arm.com> Message-ID: <20150708150914.9112.89358@quantum> User-Agent: alot/0.3.5 Subject: Re: [RFCv5 PATCH 37/46] cpufreq: introduce cpufreq_driver_might_sleep Date: Wed, 08 Jul 2015 08:09:14 -0700 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Quoting Morten Rasmussen (2015-07-07 11:24:20) > From: Michael Turquette > > Some architectures and platforms perform CPU frequency transitions > through a non-blocking method, while some might block or sleep. This > distinction is important when trying to change frequency from interrupt > context or in any other non-interruptable context, such as from the > Linux scheduler. > > Describe this distinction with a cpufreq driver flag, > CPUFREQ_DRIVER_WILL_NOT_SLEEP. The default is to not have this flag set, > thus erring on the side of caution. > > cpufreq_driver_might_sleep() is also introduced in this patch. Setting > the above flag will allow this function to return false. > > Cc: Rafael J. Wysocki > Cc: Viresh Kumar > Signed-off-by: Michael Turquette Hi Morten, I believe your sign-off is needed here as well. Regards, Mike > --- > drivers/cpufreq/cpufreq.c | 6 ++++++ > include/linux/cpufreq.h | 9 +++++++++ > 2 files changed, 15 insertions(+) > > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c > index 8ae655c..5753cb6 100644 > --- a/drivers/cpufreq/cpufreq.c > +++ b/drivers/cpufreq/cpufreq.c > @@ -112,6 +112,12 @@ bool have_governor_per_policy(void) > } > EXPORT_SYMBOL_GPL(have_governor_per_policy); > > +bool cpufreq_driver_might_sleep(void) > +{ > + return !(cpufreq_driver->flags & CPUFREQ_DRIVER_WILL_NOT_SLEEP); > +} > +EXPORT_SYMBOL_GPL(cpufreq_driver_might_sleep); > + > struct kobject *get_governor_parent_kobj(struct cpufreq_policy *policy) > { > if (have_governor_per_policy()) > diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h > index 2ee4888..1f2c9a1 100644 > --- a/include/linux/cpufreq.h > +++ b/include/linux/cpufreq.h > @@ -157,6 +157,7 @@ u64 get_cpu_idle_time(unsigned int cpu, u64 *wall, int io_busy); > int cpufreq_get_policy(struct cpufreq_policy *policy, unsigned int cpu); > int cpufreq_update_policy(unsigned int cpu); > bool have_governor_per_policy(void); > +bool cpufreq_driver_might_sleep(void); > struct kobject *get_governor_parent_kobj(struct cpufreq_policy *policy); > #else > static inline unsigned int cpufreq_get(unsigned int cpu) > @@ -314,6 +315,14 @@ struct cpufreq_driver { > */ > #define CPUFREQ_NEED_INITIAL_FREQ_CHECK (1 << 5) > > +/* > + * Set by drivers that will never block or sleep during their frequency > + * transition. Used to indicate when it is safe to call cpufreq_driver_target > + * from non-interruptable context. Drivers must opt-in to this flag, as the > + * safe default is that they might sleep. > + */ > +#define CPUFREQ_DRIVER_WILL_NOT_SLEEP (1 << 6) > + > int cpufreq_register_driver(struct cpufreq_driver *driver_data); > int cpufreq_unregister_driver(struct cpufreq_driver *driver_data); > > -- > 1.9.1 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-pm" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html