PM: EM: Move CPU capacity check to em_adjust_new_capacity()

JIRA: https://issues.redhat.com/browse/RHEL-110833

commit 3e3ba65
Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Date:   Tue May 6 22:39:35 2025 +0200

    PM: EM: Move CPU capacity check to em_adjust_new_capacity()

    Move the check of the CPU capacity currently stored in the energy model
    against the arch_scale_cpu_capacity() value to em_adjust_new_capacity()
    so it will be done regardless of where the latter is called from.

    This will be useful when a new em_adjust_new_capacity() caller is added
    subsequently.

    While at it, move the pd local variable declaration in
    em_check_capacity_update() into the loop in which it is used.

    No intentional functional impact.

    Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
    Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>
    Tested-by: Christian Loehle <christian.loehle@arm.com>
    Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
    Link: https://patch.msgid.link/7810787.EvYhyI6sBW@rjwysocki.net

Signed-off-by: Steve Best <sbest@redhat.com>

Author: sfbest

kernel/power/energy_model.c

@@ -725,10 +725,24 @@ static int em_recalc_and_update(struct device *dev, struct em_perf_domain *pd,
  * Adjustment of CPU performance values after boot, when all CPUs capacites
  * are correctly calculated.
  */
-static void em_adjust_new_capacity(struct device *dev,
+static void em_adjust_new_capacity(unsigned int cpu, struct device *dev,
 				   struct em_perf_domain *pd)
 {
+	unsigned long cpu_capacity = arch_scale_cpu_capacity(cpu);
 	struct em_perf_table *em_table;
+	struct em_perf_state *table;
+	unsigned long em_max_perf;
+
+	rcu_read_lock();
+	table = em_perf_state_from_pd(pd);
+	em_max_perf = table[pd->nr_perf_states - 1].performance;
+	rcu_read_unlock();
+
+	if (em_max_perf == cpu_capacity)
+		return;
+
+	pr_debug("updating cpu%d cpu_cap=%lu old capacity=%lu\n", cpu,
+		 cpu_capacity, em_max_perf);
 
 	em_table = em_table_dup(pd);
 	if (!em_table) {
@@ -744,9 +758,6 @@ static void em_adjust_new_capacity(struct device *dev,
 static void em_check_capacity_update(void)
 {
 	cpumask_var_t cpu_done_mask;
-	struct em_perf_state *table;
-	struct em_perf_domain *pd;
-	unsigned long cpu_capacity;
 	int cpu;
 
 	if (!zalloc_cpumask_var(&cpu_done_mask, GFP_KERNEL)) {
@@ -757,7 +768,7 @@ static void em_check_capacity_update(void)
 	/* Check if CPUs capacity has changed than update EM */
 	for_each_possible_cpu(cpu) {
 		struct cpufreq_policy *policy;
-		unsigned long em_max_perf;
+		struct em_perf_domain *pd;
 		struct device *dev;
 
 		if (cpumask_test_cpu(cpu, cpu_done_mask))
@@ -780,24 +791,7 @@ static void em_check_capacity_update(void)
 		cpumask_or(cpu_done_mask, cpu_done_mask,
 			   em_span_cpus(pd));
 
-		cpu_capacity = arch_scale_cpu_capacity(cpu);
-
-		rcu_read_lock();
-		table = em_perf_state_from_pd(pd);
-		em_max_perf = table[pd->nr_perf_states - 1].performance;
-		rcu_read_unlock();
-
-		/*
-		 * Check if the CPU capacity has been adjusted during boot
-		 * and trigger the update for new performance values.
-		 */
-		if (em_max_perf == cpu_capacity)
-			continue;
-
-		pr_debug("updating cpu%d cpu_cap=%lu old capacity=%lu\n",
-			 cpu, cpu_capacity, em_max_perf);
-
-		em_adjust_new_capacity(dev, pd);
+		em_adjust_new_capacity(cpu, dev, pd);
 	}
 
 	free_cpumask_var(cpu_done_mask);