Merge branch 'pm-em' into linux-next

* pm-em:
  PM: EM: Introduce em_adjust_cpu_capacity()
  PM: EM: Move CPU capacity check to em_adjust_new_capacity()
  PM: EM: Documentation: Fix typos in example driver code
  PM: EM: Documentation: fix typo in energy-model.rst
  PM: EM: Fix potential division-by-zero error in em_compute_costs()

Author: rafaeljw

Documentation/power/energy-model.rst

@@ -230,7 +230,7 @@ Drivers must provide a pointer to the allocated and initialized new EM
 and will be visible to other sub-systems in the kernel (thermal, powercap).
 The main design goal for this API is to be fast and avoid extra calculations
 or memory allocations at runtime. When pre-computed EMs are available in the
-device driver, than it should be possible to simply re-use them with low
+device driver, then it should be possible to simply reuse them with low
 performance overhead.
 
 In order to free the EM, provided earlier by the driver (e.g. when the module
@@ -381,17 +381,17 @@ up periodically to check the temperature and modify the EM data::
   26		rcu_read_unlock();
   27
   28		/* Calculate 'cost' values for EAS */
-  29		ret = em_dev_compute_costs(dev, table, pd->nr_perf_states);
+  29		ret = em_dev_compute_costs(dev, new_table, pd->nr_perf_states);
   30		if (ret) {
   31			dev_warn(dev, "EM: compute costs failed %d\n", ret);
-  32			em_free_table(em_table);
+  32			em_table_free(em_table);
   33			return;
   34		}
   35
   36		ret = em_dev_update_perf_domain(dev, em_table);
   37		if (ret) {
   38			dev_warn(dev, "EM: update failed %d\n", ret);
-  39			em_free_table(em_table);
+  39			em_table_free(em_table);
   40			return;
   41		}
   42

include/linux/energy_model.h

@@ -179,6 +179,7 @@ int em_dev_compute_costs(struct device *dev, struct em_perf_state *table,
 int em_dev_update_chip_binning(struct device *dev);
 int em_update_performance_limits(struct em_perf_domain *pd,
 		unsigned long freq_min_khz, unsigned long freq_max_khz);
+void em_adjust_cpu_capacity(unsigned int cpu);
 void em_rebuild_sched_domains(void);
 
 /**
@@ -403,6 +404,7 @@ int em_update_performance_limits(struct em_perf_domain *pd,
 {
 	return -EINVAL;
 }
+static inline void em_adjust_cpu_capacity(unsigned int cpu) {}
 static inline void em_rebuild_sched_domains(void) {}
 #endif
 

kernel/power/energy_model.c

@@ -233,6 +233,10 @@ static int em_compute_costs(struct device *dev, struct em_perf_state *table,
 	unsigned long prev_cost = ULONG_MAX;
 	int i, ret;
 
+	/* This is needed only for CPUs and EAS skip other devices */
+	if (!_is_cpu_device(dev))
+		return 0;
+
 	/* Compute the cost of each performance state. */
 	for (i = nr_states - 1; i >= 0; i--) {
 		unsigned long power_res, cost;
@@ -698,10 +702,12 @@ static int em_recalc_and_update(struct device *dev, struct em_perf_domain *pd,
 {
 	int ret;
 
-	ret = em_compute_costs(dev, em_table->state, NULL, pd->nr_perf_states,
-			       pd->flags);
-	if (ret)
-		goto free_em_table;
+	if (!em_is_artificial(pd)) {
+		ret = em_compute_costs(dev, em_table->state, NULL,
+				       pd->nr_perf_states, pd->flags);
+		if (ret)
+			goto free_em_table;
+	}
 
 	ret = em_dev_update_perf_domain(dev, em_table);
 	if (ret)
@@ -721,10 +727,24 @@ 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) {
@@ -737,12 +757,27 @@ static void em_adjust_new_capacity(struct device *dev,
 	em_recalc_and_update(dev, pd, em_table);
 }
 
+/**
+ * em_adjust_cpu_capacity() - Adjust the EM for a CPU after a capacity update.
+ * @cpu: Target CPU.
+ *
+ * Adjust the existing EM for @cpu after a capacity update under the assumption
+ * that the capacity has been updated in the same way for all of the CPUs in
+ * the same perf domain.
+ */
+void em_adjust_cpu_capacity(unsigned int cpu)
+{
+	struct device *dev = get_cpu_device(cpu);
+	struct em_perf_domain *pd;
+
+	pd = em_pd_get(dev);
+	if (pd)
+		em_adjust_new_capacity(cpu, dev, pd);
+}
+
 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)) {
@@ -753,7 +788,7 @@ 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))
@@ -776,24 +811,7 @@ 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);