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Message-ID: <CAPDyKFra=9y58dzicL0PkwwMNWZDXaJB1+YX_ujOBeP6hrBLcA@mail.gmail.com>
Date: Mon, 17 Jun 2019 11:23:38 +0200
From: Ulf Hansson <ulf.hansson@...aro.org>
To: Viresh Kumar <viresh.kumar@...aro.org>
Cc: Rafael Wysocki <rjw@...ysocki.net>,
Linux PM <linux-pm@...r.kernel.org>,
Vincent Guittot <vincent.guittot@...aro.org>,
Qais.Yousef@....com, Matthias Kaehlcke <mka@...omium.org>,
juri.lelli@...il.com,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V3 4/5] cpufreq: Register notifiers with the PM QoS framework
On Mon, 10 Jun 2019 at 12:52, Viresh Kumar <viresh.kumar@...aro.org> wrote:
>
> This registers the 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.
>
> No constraints are added until now though.
>
> Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
Reviewed-by: Ulf Hansson <ulf.hansson@...aro.org>
Kind regards
Uffe
> ---
> drivers/cpufreq/cpufreq.c | 139 +++++++++++++++++++++++++++++++-------
> include/linux/cpufreq.h | 4 ++
> 2 files changed, 120 insertions(+), 23 deletions(-)
>
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index 85ff958e01f1..547d221b2ff2 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -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>
> @@ -1126,11 +1127,77 @@ static void handle_update(struct work_struct *work)
> cpufreq_update_policy(cpu);
> }
>
> +static void cpufreq_update_freq_work(struct work_struct *work)
> +{
> + struct cpufreq_policy *policy =
> + container_of(work, struct cpufreq_policy, req_work);
> + struct cpufreq_policy new_policy = *policy;
> +
> + /* We should read constraint values from QoS layer */
> + new_policy.min = 0;
> + new_policy.max = UINT_MAX;
> +
> + down_write(&policy->rwsem);
> +
> + if (!policy_is_inactive(policy))
> + cpufreq_set_policy(policy, &new_policy);
> +
> + up_write(&policy->rwsem);
> +}
> +
> +static int cpufreq_update_freq(struct cpufreq_policy *policy)
> +{
> + schedule_work(&policy->req_work);
> + return 0;
> +}
> +
> +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);
> +
> + return cpufreq_update_freq(policy);
> +}
> +
> +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);
> +
> + return cpufreq_update_freq(policy);
> +}
> +
> +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;
> @@ -1147,7 +1214,7 @@ 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
> @@ -1157,16 +1224,41 @@ 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);
> init_waitqueue_head(&policy->transition_wait);
> init_completion(&policy->kobj_unregister);
> INIT_WORK(&policy->update, handle_update);
> + INIT_WORK(&policy->req_work, cpufreq_update_freq_work);
>
> 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:
> @@ -1179,30 +1271,9 @@ 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;
>
> @@ -1214,6 +1285,10 @@ 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);
> @@ -2290,6 +2365,8 @@ 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",
> @@ -2304,11 +2381,27 @@ 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);
> diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
> index d01a74fbc4db..0fe7678da9c2 100644
> --- a/include/linux/cpufreq.h
> +++ b/include/linux/cpufreq.h
> @@ -83,6 +83,7 @@ struct cpufreq_policy {
>
> struct work_struct update; /* if update_policy() needs to be
> * called, but you're in IRQ context */
> + struct work_struct req_work;
>
> struct cpufreq_user_policy user_policy;
> struct cpufreq_frequency_table *freq_table;
> @@ -147,6 +148,9 @@ 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 {
> --
> 2.21.0.rc0.269.g1a574e7a288b
>
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