cpufreq: Introduce CPUFREQ_NEED_UPDATE_LIMITS driver flag (1c534352) · Commits · 戴 / test

Generally, a cpufreq driver may need to update some internal upper and lower frequency boundaries on policy max and min changes, respectively, but currently this does not work if the target frequency does not change along with the policy limit. Namely, if the target frequency does not change along with the policy min or max, the "target_freq == policy->cur" check in __cpufreq_driver_target() prevents driver callbacks from being invoked and they do not even have a chance to update the corresponding internal boundary. This particularly affects the "powersave" and "performance" governors that always set the target frequency to one of the policy limits and it never changes when the other limit is updated. To allow cpufreq the drivers needing to update internal frequency boundaries on policy limits changes to avoid this issue, introduce a new driver flag, CPUFREQ_NEED_UPDATE_LIMITS, that (when set) will neutralize the check mentioned above. Signed-off-by:

Rafael J. Wysocki <rafael.j.wysocki@intel.com> Acked-by:

Viresh Kumar <viresh.kumar@linaro.org>

drivers/cpufreq/cpufreq.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -2187,7 +2187,8 @@ int __cpufreq_driver_target(struct cpufreq_policy *policy,
		* exactly same freq is called again and so we can save on few function
		* calls.
		*/
		if (target_freq == policy->cur)
		if (target_freq == policy->cur &&
		!(cpufreq_driver->flags & CPUFREQ_NEED_UPDATE_LIMITS))
		return 0;

		/* Save last value to restore later on errors */

include/linux/cpufreq.h

+9 −1

Original line number	Diff line number	Diff line
		@@ -298,7 +298,7 @@ __ATTR(_name, 0644, show_##_name, store_##_name)

		struct cpufreq_driver {
		char name[CPUFREQ_NAME_LEN];
		u8 flags;
		u16 flags;
		void *driver_data;

		/* needed by all drivers */
		@@ -422,6 +422,14 @@ struct cpufreq_driver {
		*/
		#define CPUFREQ_IS_COOLING_DEV BIT(7)

		/*
		* Set by drivers that need to update internale upper and lower boundaries along
		* with the target frequency and so the core and governors should also invoke
		* the diver if the target frequency does not change, but the policy min or max
		* may have changed.
		*/
		#define CPUFREQ_NEED_UPDATE_LIMITS BIT(8)

		int cpufreq_register_driver(struct cpufreq_driver *driver_data);
		int cpufreq_unregister_driver(struct cpufreq_driver *driver_data);

Admin message