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Message-ID: <89a56998-51f2-0dc3-54e8-2bc2217d265d@quicinc.com>
Date: Tue, 4 Jun 2024 00:18:14 +0530
From: Sibi Sankar <quic_sibis@...cinc.com>
To: Vincent Guittot <vincent.guittot@...aro.org>
CC: <sudeep.holla@....com>, <cristian.marussi@....com>, <rafael@...nel.org>,
<viresh.kumar@...aro.org>, <morten.rasmussen@....com>,
<dietmar.eggemann@....com>, <lukasz.luba@....com>,
<pierre.gondois@....com>, <linux-arm-kernel@...ts.infradead.org>,
<linux-pm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<quic_mdtipton@...cinc.com>, <linux-arm-msm@...r.kernel.org>
Subject: Re: [PATCH V4 2/2] cpufreq: scmi: Register for limit change
notifications
On 5/28/24 14:38, Vincent Guittot wrote:
> Hi Sibi,
>
Hey Vincent,
Thanks for taking time to review the series :)
> On Thu, 28 Mar 2024 at 08:42, Sibi Sankar <quic_sibis@...cinc.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@...cinc.com>
>> ---
>>
>> v4:
>> * Use a interim variable to show the khz calc. [Lukasz]
>> * Use driver_data to pass on the handle and scmi_dev instead of using
>> global variables. Dropped Lukasz's Rb due to adding these minor
>> changes.
>>
>> drivers/cpufreq/scmi-cpufreq.c | 44 ++++++++++++++++++++++++++++++++++
>> 1 file changed, 44 insertions(+)
>>
>> diff --git a/drivers/cpufreq/scmi-cpufreq.c b/drivers/cpufreq/scmi-cpufreq.c
>> index 3b4f6bfb2f4c..d946b7a08258 100644
>> --- a/drivers/cpufreq/scmi-cpufreq.c
>> +++ b/drivers/cpufreq/scmi-cpufreq.c
>> @@ -21,11 +21,18 @@
>> #include <linux/types.h>
>> #include <linux/units.h>
>>
>> +struct scmi_cpufreq_driver_data {
>> + struct scmi_device *sdev;
>> + const struct scmi_handle *handle;
>> +};
>> +
>> 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 +181,22 @@ 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;
>> +
>> + 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);
>> +
>> + cpufreq_update_pressure(policy);
>
> I noticed your patch while looking for other things in the archive but
> I don't think this is the right way to do it.
>
> cpufreq_update_pressure() aims to set to the scheduler the aggregation
> of all cappings set to cpufreq through the pm_qos and
> freq_qos_add_request(). Calling this function directly in scmi
> notification callback will overwrite the pm_qos aggregation. And at
> the opposite, any update of a pm_qos constraint will overwrite scmi
> notification. Instead you should better set a pm_qos constraint like
> others
Sure, I'll drop update_pressue and use the freq_qos_update_request to
update the policy->max_freq_req with the new policy->max.
-Sibi
>
>> +
>> + 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_cpufreq_driver_data *data = cpufreq_get_driver_data();
>>
>> cpu_dev = get_cpu_device(policy->cpu);
>> if (!cpu_dev) {
>> @@ -294,6 +318,17 @@ static int scmi_cpufreq_init(struct cpufreq_policy *policy)
>> }
>> }
>>
>> + priv->limit_notify_nb.notifier_call = scmi_limit_notify_cb;
>> + ret = data->handle->notify_ops->devm_event_notifier_register(data->sdev, SCMI_PROTOCOL_PERF,
>> + SCMI_EVENT_PERFORMANCE_LIMITS_CHANGED,
>> + &domain,
>> + &priv->limit_notify_nb);
>> + if (ret)
>> + dev_warn(cpu_dev,
>> + "failed to register for limits change notifier for domain %d\n", domain);
>> +
>> + priv->policy = policy;
>> +
>> return 0;
>>
>> out_free_opp:
>> @@ -366,12 +401,21 @@ static int scmi_cpufreq_probe(struct scmi_device *sdev)
>> int ret;
>> struct device *dev = &sdev->dev;
>> const struct scmi_handle *handle;
>> + struct scmi_cpufreq_driver_data *data;
>>
>> handle = sdev->handle;
>>
>> if (!handle)
>> return -ENODEV;
>>
>> + data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
>> + if (!data)
>> + return -ENOMEM;
>> +
>> + data->sdev = sdev;
>> + data->handle = handle;
>> + scmi_cpufreq_driver.driver_data = data;
>> +
>> perf_ops = handle->devm_protocol_get(sdev, SCMI_PROTOCOL_PERF, &ph);
>> if (IS_ERR(perf_ops))
>> return PTR_ERR(perf_ops);
>> --
>> 2.34.1
>>
>>
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