PM / EM: change name of em_pd_energy to em_cpu_energy

Energy Model framework now supports other devices than CPUs. Refactor some
of the functions in order to prevent wrong usage. The old function
em_pd_energy has to generic name. It must not be used without proper
cpumask pointer, which is possible only for CPU devices. Thus, rename it
and add proper description to warn of potential wrong usage for other
devices.

Acked-by: Daniel Lezcano <[email protected]>
Acked-by: Quentin Perret <[email protected]>
Signed-off-by: Lukasz Luba <[email protected]>
Signed-off-by: Rafael J. Wysocki <[email protected]>

Author: lukaszluba-arm

include/linux/energy_model.h

@@ -83,15 +83,20 @@ int em_dev_register_perf_domain(struct device *dev, unsigned int nr_states,
 void em_dev_unregister_perf_domain(struct device *dev);
 
 /**
- * em_pd_energy() - Estimates the energy consumed by the CPUs of a perf. domain
+ * em_cpu_energy() - Estimates the energy consumed by the CPUs of a
+		performance domain
  * @pd		: performance domain for which energy has to be estimated
  * @max_util	: highest utilization among CPUs of the domain
  * @sum_util	: sum of the utilization of all CPUs in the domain
  *
+ * This function must be used only for CPU devices. There is no validation,
+ * i.e. if the EM is a CPU type and has cpumask allocated. It is called from
+ * the scheduler code quite frequently and that is why there is not checks.
+ *
  * Return: the sum of the energy consumed by the CPUs of the domain assuming
  * a capacity state satisfying the max utilization of the domain.
  */
-static inline unsigned long em_pd_energy(struct em_perf_domain *pd,
+static inline unsigned long em_cpu_energy(struct em_perf_domain *pd,
 				unsigned long max_util, unsigned long sum_util)
 {
 	unsigned long freq, scale_cpu;
@@ -196,7 +201,7 @@ static inline struct em_perf_domain *em_pd_get(struct device *dev)
 {
 	return NULL;
 }
-static inline unsigned long em_pd_energy(struct em_perf_domain *pd,
+static inline unsigned long em_cpu_energy(struct em_perf_domain *pd,
 			unsigned long max_util, unsigned long sum_util)
 {
 	return 0;

kernel/sched/fair.c

@@ -6497,7 +6497,7 @@ compute_energy(struct task_struct *p, int dst_cpu, struct perf_domain *pd)
 		max_util = max(max_util, cpu_util);
 	}
 
-	return em_pd_energy(pd->em_pd, max_util, sum_util);
+	return em_cpu_energy(pd->em_pd, max_util, sum_util);
 }
 
 /*