[PATCH V7 2/2] cpufreq: scmi: Register for limit change notifications

[Sibi Sankar]

On 11/3/24 20:42, Vincent Guittot wrote:
> On Thu, 31 Oct 2024 at 14:28, Sibi Sankar <quic_sibis at quicinc.com> wrote:
>>
>> Register for limit change notifications if supported and use the throttled
>> frequency from the notification to apply HW pressure.
>>
>> Signed-off-by: Sibi Sankar <quic_sibis at quicinc.com>
>> Tested-by: Mike Tipton <quic_mdtipton at quicinc.com>
>> Reviewed-by: Cristian Marussi <cristian.marussi at arm.com>
>> Reviewed-by: Lukasz Luba <lukasz.luba at arm.com>
>> ---
>>
>> v7:
>> * Add a new request instead of reusing the max_freq_req [Vincent]
>> * Use the non-devm versions of register/unregister of event notifier
>>    since we have to remove them when the cpus get removed anyway.
>> * Add new patch to fix cleanup path on boost enablement failure.
>>
>>   drivers/cpufreq/scmi-cpufreq.c | 51 ++++++++++++++++++++++++++++++++++
>>   1 file changed, 51 insertions(+)
>>
>> diff --git a/drivers/cpufreq/scmi-cpufreq.c b/drivers/cpufreq/scmi-cpufreq.c
>> index 07d6f9a9b7c8..ff13f7d4b2c9 100644
>> --- a/drivers/cpufreq/scmi-cpufreq.c
>> +++ b/drivers/cpufreq/scmi-cpufreq.c
>> @@ -16,6 +16,7 @@
>>   #include <linux/export.h>
>>   #include <linux/module.h>
>>   #include <linux/pm_opp.h>
>> +#include <linux/pm_qos.h>
>>   #include <linux/slab.h>
>>   #include <linux/scmi_protocol.h>
>>   #include <linux/types.h>
>> @@ -25,7 +26,10 @@ struct scmi_data {
>>          int domain_id;
>>          int nr_opp;
>>          struct device *cpu_dev;
>> +       struct cpufreq_policy *policy;
>>          cpumask_var_t opp_shared_cpus;
>> +       struct notifier_block limit_notify_nb;
>> +       struct freq_qos_request limits_freq_req;
>>   };
>>
>>   static struct scmi_protocol_handle *ph;
>> @@ -174,6 +178,25 @@ static struct freq_attr *scmi_cpufreq_hw_attr[] = {
>>          NULL,
>>   };
>>
>> +static int scmi_limit_notify_cb(struct notifier_block *nb, unsigned long event, void *data)
>> +{
>> +       struct scmi_data *priv = container_of(nb, struct scmi_data, limit_notify_nb);
>> +       struct scmi_perf_limits_report *limit_notify = data;
>> +       struct cpufreq_policy *policy = priv->policy;
>> +       unsigned int limit_freq_khz;
>> +       int ret;
>> +
>> +       limit_freq_khz = limit_notify->range_max_freq / HZ_PER_KHZ;
>> +
>> +       policy->max = clamp(limit_freq_khz, policy->cpuinfo.min_freq, policy->cpuinfo.max_freq);
> 
> I don't think that the above is needed or correct, the cpufreq qos
> notifier will take care of updating policy->max with handle_update()

Fixed this in the next re-spin. Thanks again for the review.

-Sibi

> 
>> +
>> +       ret = freq_qos_update_request(&priv->limits_freq_req, policy->max);
>> +       if (ret < 0)
>> +               pr_warn("failed to update freq constraint: %d\n", ret);
>> +
>> +       return NOTIFY_OK;
>> +}
>> +
>>   static int scmi_cpufreq_init(struct cpufreq_policy *policy)
>>   {
>>          int ret, nr_opp, domain;
>> @@ -181,6 +204,7 @@ static int scmi_cpufreq_init(struct cpufreq_policy *policy)
>>          struct device *cpu_dev;
>>          struct scmi_data *priv;
>>          struct cpufreq_frequency_table *freq_table;
>> +       struct scmi_device *sdev = cpufreq_get_driver_data();
>>
>>          cpu_dev = get_cpu_device(policy->cpu);
>>          if (!cpu_dev) {
>> @@ -294,6 +318,25 @@ static int scmi_cpufreq_init(struct cpufreq_policy *policy)
>>                  }
>>          }
>>
>> +       ret = freq_qos_add_request(&policy->constraints, &priv->limits_freq_req, FREQ_QOS_MAX,
>> +                                  FREQ_QOS_MAX_DEFAULT_VALUE);
>> +       if (ret < 0) {
>> +               dev_err(cpu_dev, "failed to add qos limits request: %d\n", ret);
>> +               goto out_free_table;
>> +       }
>> +
>> +       priv->limit_notify_nb.notifier_call = scmi_limit_notify_cb;
>> +       ret = sdev->handle->notify_ops->event_notifier_register(sdev->handle, SCMI_PROTOCOL_PERF,
>> +                                                       SCMI_EVENT_PERFORMANCE_LIMITS_CHANGED,
>> +                                                       &priv->domain_id,
>> +                                                       &priv->limit_notify_nb);
>> +       if (ret)
>> +               dev_warn(&sdev->dev,
>> +                        "failed to register for limits change notifier for domain %d\n",
>> +                        priv->domain_id);
>> +
>> +       priv->policy = policy;
>> +
>>          return 0;
>>
>>   out_free_table:
>> @@ -313,7 +356,13 @@ static int scmi_cpufreq_init(struct cpufreq_policy *policy)
>>   static void scmi_cpufreq_exit(struct cpufreq_policy *policy)
>>   {
>>          struct scmi_data *priv = policy->driver_data;
>> +       struct scmi_device *sdev = cpufreq_get_driver_data();
>>
>> +       sdev->handle->notify_ops->event_notifier_unregister(sdev->handle, SCMI_PROTOCOL_PERF,
>> +                                                           SCMI_EVENT_PERFORMANCE_LIMITS_CHANGED,
>> +                                                           &priv->domain_id,
>> +                                                           &priv->limit_notify_nb);
>> +       freq_qos_remove_request(&priv->limits_freq_req);
>>          dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table);
>>          dev_pm_opp_remove_all_dynamic(priv->cpu_dev);
>>          free_cpumask_var(priv->opp_shared_cpus);
>> @@ -372,6 +421,8 @@ static int scmi_cpufreq_probe(struct scmi_device *sdev)
>>          if (!handle)
>>                  return -ENODEV;
>>
>> +       scmi_cpufreq_driver.driver_data = sdev;
>> +
>>          perf_ops = handle->devm_protocol_get(sdev, SCMI_PROTOCOL_PERF, &ph);
>>          if (IS_ERR(perf_ops))
>>                  return PTR_ERR(perf_ops);
>> --
>> 2.34.1
>>