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cpufreq: Register notifiers with the PM QoS framework
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Register notifiers for min/max frequency constraints with the PM QoS
framework. The constraints are also taken into consideration in
cpufreq_set_policy().

This also relocates cpufreq_policy_put_kobj() as it is required to be
called from cpufreq_policy_alloc() now.

refresh_frequency_limits() is updated to avoid calling
cpufreq_set_policy() for inactive policies and handle_update() is
updated to have proper locking in place.

No constraints are added until now though.

Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Tested-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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@vireshk @rafaeljw
vireshk authored and rafaeljw committed Jul 8, 2019
1 parent 208637b commit 67d874c
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Showing 2 changed files with 108 additions and 30 deletions.
135 changes: 105 additions & 30 deletions drivers/cpufreq/cpufreq.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,7 @@
#include <linux/kernel_stat.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/pm_qos.h>
#include <linux/slab.h>
#include <linux/suspend.h>
#include <linux/syscore_ops.h>
Expand Down Expand Up @@ -999,7 +1000,7 @@ static void add_cpu_dev_symlink(struct cpufreq_policy *policy, unsigned int cpu)
{
struct device *dev = get_cpu_device(cpu);

if (!dev)
if (unlikely(!dev))
return;

if (cpumask_test_and_set_cpu(cpu, policy->real_cpus))
Expand Down Expand Up @@ -1117,14 +1118,16 @@ static int cpufreq_add_policy_cpu(struct cpufreq_policy *policy, unsigned int cp

static void refresh_frequency_limits(struct cpufreq_policy *policy)
{
struct cpufreq_policy new_policy = *policy;

pr_debug("updating policy for CPU %u\n", policy->cpu);
struct cpufreq_policy new_policy;

new_policy.min = policy->user_policy.min;
new_policy.max = policy->user_policy.max;
if (!policy_is_inactive(policy)) {
new_policy = *policy;
pr_debug("updating policy for CPU %u\n", policy->cpu);

cpufreq_set_policy(policy, &new_policy);
new_policy.min = policy->user_policy.min;
new_policy.max = policy->user_policy.max;
cpufreq_set_policy(policy, &new_policy);
}
}

static void handle_update(struct work_struct *work)
Expand All @@ -1133,14 +1136,60 @@ static void handle_update(struct work_struct *work)
container_of(work, struct cpufreq_policy, update);

pr_debug("handle_update for cpu %u called\n", policy->cpu);
down_write(&policy->rwsem);
refresh_frequency_limits(policy);
up_write(&policy->rwsem);
}

static int cpufreq_notifier_min(struct notifier_block *nb, unsigned long freq,
void *data)
{
struct cpufreq_policy *policy = container_of(nb, struct cpufreq_policy, nb_min);

schedule_work(&policy->update);
return 0;
}

static int cpufreq_notifier_max(struct notifier_block *nb, unsigned long freq,
void *data)
{
struct cpufreq_policy *policy = container_of(nb, struct cpufreq_policy, nb_max);

schedule_work(&policy->update);
return 0;
}

static void cpufreq_policy_put_kobj(struct cpufreq_policy *policy)
{
struct kobject *kobj;
struct completion *cmp;

down_write(&policy->rwsem);
cpufreq_stats_free_table(policy);
kobj = &policy->kobj;
cmp = &policy->kobj_unregister;
up_write(&policy->rwsem);
kobject_put(kobj);

/*
* We need to make sure that the underlying kobj is
* actually not referenced anymore by anybody before we
* proceed with unloading.
*/
pr_debug("waiting for dropping of refcount\n");
wait_for_completion(cmp);
pr_debug("wait complete\n");
}

static struct cpufreq_policy *cpufreq_policy_alloc(unsigned int cpu)
{
struct cpufreq_policy *policy;
struct device *dev = get_cpu_device(cpu);
int ret;

if (!dev)
return NULL;

policy = kzalloc(sizeof(*policy), GFP_KERNEL);
if (!policy)
return NULL;
Expand All @@ -1157,7 +1206,7 @@ static struct cpufreq_policy *cpufreq_policy_alloc(unsigned int cpu)
ret = kobject_init_and_add(&policy->kobj, &ktype_cpufreq,
cpufreq_global_kobject, "policy%u", cpu);
if (ret) {
pr_err("%s: failed to init policy->kobj: %d\n", __func__, ret);
dev_err(dev, "%s: failed to init policy->kobj: %d\n", __func__, ret);
/*
* The entire policy object will be freed below, but the extra
* memory allocated for the kobject name needs to be freed by
Expand All @@ -1167,6 +1216,25 @@ static struct cpufreq_policy *cpufreq_policy_alloc(unsigned int cpu)
goto err_free_real_cpus;
}

policy->nb_min.notifier_call = cpufreq_notifier_min;
policy->nb_max.notifier_call = cpufreq_notifier_max;

ret = dev_pm_qos_add_notifier(dev, &policy->nb_min,
DEV_PM_QOS_MIN_FREQUENCY);
if (ret) {
dev_err(dev, "Failed to register MIN QoS notifier: %d (%*pbl)\n",
ret, cpumask_pr_args(policy->cpus));
goto err_kobj_remove;
}

ret = dev_pm_qos_add_notifier(dev, &policy->nb_max,
DEV_PM_QOS_MAX_FREQUENCY);
if (ret) {
dev_err(dev, "Failed to register MAX QoS notifier: %d (%*pbl)\n",
ret, cpumask_pr_args(policy->cpus));
goto err_min_qos_notifier;
}

INIT_LIST_HEAD(&policy->policy_list);
init_rwsem(&policy->rwsem);
spin_lock_init(&policy->transition_lock);
Expand All @@ -1177,6 +1245,11 @@ static struct cpufreq_policy *cpufreq_policy_alloc(unsigned int cpu)
policy->cpu = cpu;
return policy;

err_min_qos_notifier:
dev_pm_qos_remove_notifier(dev, &policy->nb_min,
DEV_PM_QOS_MIN_FREQUENCY);
err_kobj_remove:
cpufreq_policy_put_kobj(policy);
err_free_real_cpus:
free_cpumask_var(policy->real_cpus);
err_free_rcpumask:
Expand All @@ -1189,30 +1262,9 @@ static struct cpufreq_policy *cpufreq_policy_alloc(unsigned int cpu)
return NULL;
}

static void cpufreq_policy_put_kobj(struct cpufreq_policy *policy)
{
struct kobject *kobj;
struct completion *cmp;

down_write(&policy->rwsem);
cpufreq_stats_free_table(policy);
kobj = &policy->kobj;
cmp = &policy->kobj_unregister;
up_write(&policy->rwsem);
kobject_put(kobj);

/*
* We need to make sure that the underlying kobj is
* actually not referenced anymore by anybody before we
* proceed with unloading.
*/
pr_debug("waiting for dropping of refcount\n");
wait_for_completion(cmp);
pr_debug("wait complete\n");
}

static void cpufreq_policy_free(struct cpufreq_policy *policy)
{
struct device *dev = get_cpu_device(policy->cpu);
unsigned long flags;
int cpu;

Expand All @@ -1224,6 +1276,11 @@ static void cpufreq_policy_free(struct cpufreq_policy *policy)
per_cpu(cpufreq_cpu_data, cpu) = NULL;
write_unlock_irqrestore(&cpufreq_driver_lock, flags);

dev_pm_qos_remove_notifier(dev, &policy->nb_max,
DEV_PM_QOS_MAX_FREQUENCY);
dev_pm_qos_remove_notifier(dev, &policy->nb_min,
DEV_PM_QOS_MIN_FREQUENCY);

cpufreq_policy_put_kobj(policy);
free_cpumask_var(policy->real_cpus);
free_cpumask_var(policy->related_cpus);
Expand Down Expand Up @@ -2283,6 +2340,8 @@ int cpufreq_set_policy(struct cpufreq_policy *policy,
struct cpufreq_policy *new_policy)
{
struct cpufreq_governor *old_gov;
struct device *cpu_dev = get_cpu_device(policy->cpu);
unsigned long min, max;
int ret;

pr_debug("setting new policy for CPU %u: %u - %u kHz\n",
Expand All @@ -2297,11 +2356,27 @@ int cpufreq_set_policy(struct cpufreq_policy *policy,
if (new_policy->min > new_policy->max)
return -EINVAL;

/*
* PM QoS framework collects all the requests from users and provide us
* the final aggregated value here.
*/
min = dev_pm_qos_read_value(cpu_dev, DEV_PM_QOS_MIN_FREQUENCY);
max = dev_pm_qos_read_value(cpu_dev, DEV_PM_QOS_MAX_FREQUENCY);

if (min > new_policy->min)
new_policy->min = min;
if (max < new_policy->max)
new_policy->max = max;

/* verify the cpu speed can be set within this limit */
ret = cpufreq_driver->verify(new_policy);
if (ret)
return ret;

/*
* The notifier-chain shall be removed once all the users of
* CPUFREQ_ADJUST are moved to use the QoS framework.
*/
/* adjust if necessary - all reasons */
blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
CPUFREQ_ADJUST, new_policy);
Expand Down
3 changes: 3 additions & 0 deletions include/linux/cpufreq.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -147,6 +147,9 @@ struct cpufreq_policy {

/* Pointer to the cooling device if used for thermal mitigation */
struct thermal_cooling_device *cdev;

struct notifier_block nb_min;
struct notifier_block nb_max;
};

struct cpufreq_freqs {
Expand Down

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