[PATCH v3 4/4] PM / devfreq: passive: Keep cpufreq_policy for possible cpus

[Chanwoo Choi]

The passive governor requires the cpu data to get the next target frequency
of devfreq device if depending on cpu. In order to reduce the unnecessary
memory data, keep cpufreq_policy data for possible cpus instead of NR_CPU.

Signed-off-by: Chanwoo Choi <cw00.choi@xxxxxxxxxxx>
---
 drivers/devfreq/governor.h         |  3 ++
 drivers/devfreq/governor_passive.c | 73 ++++++++++++++++++++++++------
 include/linux/devfreq.h            |  4 +-
 3 files changed, 63 insertions(+), 17 deletions(-)

diff --git a/drivers/devfreq/governor.h b/drivers/devfreq/governor.h
index 335c4a491254..0adfebc0467a 100644
--- a/drivers/devfreq/governor.h
+++ b/drivers/devfreq/governor.h
@@ -49,6 +49,7 @@
 
 /**
  * struct devfreq_cpu_data - Hold the per-cpu data
+ * @node:	list node
  * @dev:	reference to cpu device.
  * @first_cpu:	the cpumask of the first cpu of a policy.
  * @opp_table:	reference to cpu opp table.
@@ -60,6 +61,8 @@
  * This is auto-populated by the governor.
  */
 struct devfreq_cpu_data {
+	struct list_head node;
+
 	struct device *dev;
 	unsigned int first_cpu;
 
diff --git a/drivers/devfreq/governor_passive.c b/drivers/devfreq/governor_passive.c
index db02f5219684..331e93b9eb8d 100644
--- a/drivers/devfreq/governor_passive.c
+++ b/drivers/devfreq/governor_passive.c
@@ -18,6 +18,22 @@
 
 #define HZ_PER_KHZ	1000
 
+static struct devfreq_cpu_data *
+get_parent_cpu_data(struct devfreq_passive_data *p_data,
+		    struct cpufreq_policy *policy)
+{
+	struct devfreq_cpu_data *parent_cpu_data;
+
+	if (!p_data || !policy)
+		return NULL;
+
+	list_for_each_entry(parent_cpu_data, &p_data->cpu_data_list, node)
+		if (parent_cpu_data->first_cpu == cpumask_first(policy->related_cpus))
+			return parent_cpu_data;
+
+	return NULL;
+}
+
 static unsigned long get_target_freq_by_required_opp(struct device *p_dev,
 						struct opp_table *p_opp_table,
 						struct opp_table *opp_table,
@@ -50,14 +66,24 @@ static int get_target_freq_with_cpufreq(struct devfreq *devfreq,
 	struct devfreq_passive_data *p_data =
 				(struct devfreq_passive_data *)devfreq->data;
 	struct devfreq_cpu_data *parent_cpu_data;
+	struct cpufreq_policy *policy;
 	unsigned long cpu, cpu_cur, cpu_min, cpu_max, cpu_percent;
 	unsigned long dev_min, dev_max;
 	unsigned long freq = 0;
+	int ret = 0;
 
 	for_each_online_cpu(cpu) {
-		parent_cpu_data = p_data->parent_cpu_data[cpu];
-		if (!parent_cpu_data || parent_cpu_data->first_cpu != cpu)
+		policy = cpufreq_cpu_get(cpu);
+		if (!policy) {
+			ret = -EINVAL;
+			continue;
+		}
+
+		parent_cpu_data = get_parent_cpu_data(p_data, policy);
+		if (!parent_cpu_data) {
+			cpufreq_cpu_put(policy);
 			continue;
+		}
 
 		/* Get target freq via required opps */
 		cpu_cur = parent_cpu_data->cur_freq * HZ_PER_KHZ;
@@ -66,6 +92,7 @@ static int get_target_freq_with_cpufreq(struct devfreq *devfreq,
 					devfreq->opp_table, cpu_cur);
 		if (freq) {
 			*target_freq = max(freq, *target_freq);
+			cpufreq_cpu_put(policy);
 			continue;
 		}
 
@@ -80,9 +107,10 @@ static int get_target_freq_with_cpufreq(struct devfreq *devfreq,
 		freq = dev_min + mult_frac(dev_max - dev_min, cpu_percent, 100);
 
 		*target_freq = max(freq, *target_freq);
+		cpufreq_cpu_put(policy);
 	}
 
-	return 0;
+	return ret;
 }
 
 static int get_target_freq_with_devfreq(struct devfreq *devfreq,
@@ -167,12 +195,11 @@ static int cpufreq_passive_notifier_call(struct notifier_block *nb,
 	unsigned int cur_freq;
 	int ret;
 
-	if (event != CPUFREQ_POSTCHANGE || !freqs ||
-		!p_data->parent_cpu_data[freqs->policy->cpu])
+	if (event != CPUFREQ_POSTCHANGE || !freqs)
 		return 0;
 
-	parent_cpu_data = p_data->parent_cpu_data[freqs->policy->cpu];
-	if (parent_cpu_data->cur_freq == freqs->new)
+	parent_cpu_data = get_parent_cpu_data(p_data, freqs->policy);
+	if (!parent_cpu_data || parent_cpu_data->cur_freq == freqs->new)
 		return 0;
 
 	cur_freq = parent_cpu_data->cur_freq;
@@ -195,7 +222,7 @@ static int cpufreq_passive_unregister_notifier(struct devfreq *devfreq)
 	struct devfreq_passive_data *p_data
 			= (struct devfreq_passive_data *)devfreq->data;
 	struct devfreq_cpu_data *parent_cpu_data;
-	int cpu, ret;
+	int cpu, ret = 0;
 
 	if (p_data->nb.notifier_call) {
 		ret = cpufreq_unregister_notifier(&p_data->nb,
@@ -205,16 +232,26 @@ static int cpufreq_passive_unregister_notifier(struct devfreq *devfreq)
 	}
 
 	for_each_possible_cpu(cpu) {
-		parent_cpu_data = p_data->parent_cpu_data[cpu];
-		if (!parent_cpu_data)
+		struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
+		if (!policy) {
+			ret = -EINVAL;
 			continue;
+		}
 
+		parent_cpu_data = get_parent_cpu_data(p_data, policy);
+		if (!parent_cpu_data) {
+			cpufreq_cpu_put(policy);
+			continue;
+		}
+
+		list_del(&parent_cpu_data->node);
 		if (parent_cpu_data->opp_table)
 			dev_pm_opp_put_opp_table(parent_cpu_data->opp_table);
 		kfree(parent_cpu_data);
+		cpufreq_cpu_put(policy);
 	}
 
-	return 0;
+	return ret;
 }
 
 static int cpufreq_passive_register_notifier(struct devfreq *devfreq)
@@ -232,6 +269,9 @@ static int cpufreq_passive_register_notifier(struct devfreq *devfreq)
 	if (!p_data->this)
 		p_data->this = devfreq;
 
+	p_data->cpu_data_list
+		= (struct list_head)LIST_HEAD_INIT(p_data->cpu_data_list);
+
 	p_data->nb.notifier_call = cpufreq_passive_notifier_call;
 	ret = cpufreq_register_notifier(&p_data->nb, CPUFREQ_TRANSITION_NOTIFIER);
 	if (ret) {
@@ -241,15 +281,18 @@ static int cpufreq_passive_register_notifier(struct devfreq *devfreq)
 	}
 
 	for_each_possible_cpu(cpu) {
-		if (p_data->parent_cpu_data[cpu])
-			continue;
-
 		policy = cpufreq_cpu_get(cpu);
 		if (!policy) {
 			ret = -EPROBE_DEFER;
 			goto err;
 		}
 
+		parent_cpu_data = get_parent_cpu_data(p_data, policy);
+		if (parent_cpu_data) {
+			cpufreq_cpu_put(policy);
+			continue;
+		}
+
 		parent_cpu_data = kzalloc(sizeof(*parent_cpu_data),
 						GFP_KERNEL);
 		if (!parent_cpu_data) {
@@ -278,7 +321,7 @@ static int cpufreq_passive_register_notifier(struct devfreq *devfreq)
 		parent_cpu_data->min_freq = policy->cpuinfo.min_freq;
 		parent_cpu_data->max_freq = policy->cpuinfo.max_freq;
 
-		p_data->parent_cpu_data[cpu] = parent_cpu_data;
+		list_add_tail(&parent_cpu_data->node, &p_data->cpu_data_list);
 		cpufreq_cpu_put(policy);
 	}
 
diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
index ccebb5c84d62..2fca831db564 100644
--- a/include/linux/devfreq.h
+++ b/include/linux/devfreq.h
@@ -309,7 +309,7 @@ enum devfreq_parent_dev_type {
  + * @this:		the devfreq instance of own device.
  + * @nb:		the notifier block for DEVFREQ_TRANSITION_NOTIFIER or
  *			CPUFREQ_TRANSITION_NOTIFIER list.
- + * @cpu_data:		the state min/max/current frequency of all online cpu's
+ + * @cpu_data_list:	the cpufreq_policy list of all possible cpus.
  *
  * The devfreq_passive_data have to set the devfreq instance of parent
  * device with governors except for the passive governor. But, don't need to
@@ -329,7 +329,7 @@ struct devfreq_passive_data {
 	/* For passive governor's internal use. Don't need to set them */
 	struct devfreq *this;
 	struct notifier_block nb;
-	struct devfreq_cpu_data *parent_cpu_data[NR_CPUS];
+	struct list_head cpu_data_list;
 };
 #endif
 
-- 
2.25.1