| Message ID | 1436293469-25707-38-git-send-email-morten.rasmussen@arm.com (mailing list archive) |
|---|---|
| State | RFC |
| Headers | show |
Quoting Morten Rasmussen (2015-07-07 11:24:20) > From: Michael Turquette <mturquette@baylibre.com> > > 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 <rafael@kernel.org> > Cc: Viresh Kumar <viresh.kumar@linaro.org> > Signed-off-by: Michael Turquette <mturquette@baylibre.com> 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 -- 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
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);