Commit 977230d5 authored by Lukasz Luba's avatar Lukasz Luba Committed by Rafael J. Wysocki
Browse files

PM: EM: Introduce em_dev_update_perf_domain() for EM updates 



Add API function em_dev_update_perf_domain() which allows the EM to be
changed safely.

Concurrent updaters are serialized with a mutex and the removal of memory
that will not be used any more is carried out with the help of RCU.

Reviewed-by: default avatarDietmar Eggemann <dietmar.eggemann@arm.com>
Tested-by: default avatarDietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: default avatarLukasz Luba <lukasz.luba@arm.com>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent ffcf9bce

include/linux/energy_model.h

+8 −0
Original line number Diff line number Diff line
@@ -183,6 +183,8 @@ struct em_data_callback { 


struct em_perf_domain *em_cpu_get(int cpu);

struct em_perf_domain *em_pd_get(struct device *dev);

int em_dev_update_perf_domain(struct device *dev,

			      struct em_perf_table __rcu *new_table);

int em_dev_register_perf_domain(struct device *dev, unsigned int nr_states,

				struct em_data_callback *cb, cpumask_t *span,

				bool microwatts);
@@ -376,6 +378,12 @@ struct em_perf_table __rcu *em_table_alloc(struct em_perf_domain *pd) 
	return NULL;

}

static inline void em_table_free(struct em_perf_table __rcu *table) {}

static inline

int em_dev_update_perf_domain(struct device *dev,

			      struct em_perf_table __rcu *new_table)

{

	return -EINVAL;

}

#endif



#endif

kernel/power/energy_model.c

+44 −0
Original line number Diff line number Diff line
@@ -209,6 +209,50 @@ static int em_allocate_perf_table(struct em_perf_domain *pd, 
	return 0;

}



/**

 * em_dev_update_perf_domain() - Update runtime EM table for a device

 * @dev		: Device for which the EM is to be updated

 * @new_table	: The new EM table that is going to be used from now

 *

 * Update EM runtime modifiable table for the @dev using the provided @table.

 *

 * This function uses a mutex to serialize writers, so it must not be called

 * from a non-sleeping context.

 *

 * Return 0 on success or an error code on failure.

 */

int em_dev_update_perf_domain(struct device *dev,

			      struct em_perf_table __rcu *new_table)

{

	struct em_perf_table __rcu *old_table;

	struct em_perf_domain *pd;



	if (!dev)

		return -EINVAL;



	/* Serialize update/unregister or concurrent updates */

	mutex_lock(&em_pd_mutex);



	if (!dev->em_pd) {

		mutex_unlock(&em_pd_mutex);

		return -EINVAL;

	}

	pd = dev->em_pd;



	kref_get(&new_table->kref);



	old_table = pd->em_table;

	rcu_assign_pointer(pd->em_table, new_table);



	em_cpufreq_update_efficiencies(dev, new_table->state);



	em_table_free(old_table);



	mutex_unlock(&em_pd_mutex);

	return 0;

}

EXPORT_SYMBOL_GPL(em_dev_update_perf_domain);



static int em_create_runtime_table(struct em_perf_domain *pd)

{

	struct em_perf_table __rcu *table;