On Wed, 30 Oct 2024 at 14:32, Sibi Sankar <quic_sibis@xxxxxxxxxxx> 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@xxxxxxxxxxx>
> Tested-by: Mike Tipton <quic_mdtipton@xxxxxxxxxxx>
> Reviewed-by: Cristian Marussi <cristian.marussi@xxxxxxx>
> Reviewed-by: Lukasz Luba <lukasz.luba@xxxxxxx>
> ---
>
> v6:
> * Unregister the notifier in the exit path to make sure
> the cpus work across suspend/resume cycles.
>
> drivers/cpufreq/scmi-cpufreq.c | 38 ++++++++++++++++++++++++++++++++++
> 1 file changed, 38 insertions(+)
>
> diff --git a/drivers/cpufreq/scmi-cpufreq.c b/drivers/cpufreq/scmi-cpufreq.c
> index 5892c73e129d..fb3534eae722 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 +26,9 @@ 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;
> };
>
> static struct scmi_protocol_handle *ph;
> @@ -174,6 +177,25 @@ 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);
> +
> + ret = freq_qos_update_request(policy->max_freq_req, policy->max);
If I don't get it wrong, you are using policy->max_freq_req which is
also used by the sysfs scaling_max_freq
This means that your request will be overwritten by the next write
into scaling_max_freq and/or you will overwrite a constraint set by
userspace.
You have to create your own freq_qos_request and add it to the list of
cpufreq qos request
> + 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 +203,7 @@ 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 +317,17 @@ static int scmi_cpufreq_init(struct cpufreq_policy *policy)
> }
> }
>
> + priv->limit_notify_nb.notifier_call = scmi_limit_notify_cb;
> + ret = sdev->handle->notify_ops->devm_event_notifier_register(sdev, SCMI_PROTOCOL_PERF,
> + SCMI_EVENT_PERFORMANCE_LIMITS_CHANGED,
> + &domain,
> + &priv->limit_notify_nb);
> + if (ret)
> + dev_warn(&sdev->dev,
> + "failed to register for limits change notifier for domain %d\n", domain);
> +
> + priv->policy = policy;
> +
> return 0;
>
> out_free_opp:
> @@ -310,8 +344,10 @@ static int scmi_cpufreq_init(struct cpufreq_policy *policy)
>
> static void scmi_cpufreq_exit(struct cpufreq_policy *policy)
> {
> + struct scmi_device *sdev = cpufreq_get_driver_data();
> struct scmi_data *priv = policy->driver_data;
>
> + sdev->handle->notify_ops->devm_event_notifier_unregister(sdev, &priv->limit_notify_nb);
> 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);
> @@ -370,6 +406,8 @@ 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
>
