linux-kernel - Re: [PATCH V5 1/1] cpufreq: scmi: Register for limit change notifications

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Message-ID: <20241016234514.GA17864@hu-mdtipton-lv.qualcomm.com>
Date: Wed, 16 Oct 2024 16:45:15 -0700
From: Mike Tipton <quic_mdtipton@...cinc.com>
To: Sibi Sankar <quic_sibis@...cinc.com>
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>, <vincent.guittot@...aro.org>,
        <linux-arm-kernel@...ts.infradead.org>, <linux-pm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linux-arm-msm@...r.kernel.org>
Subject: Re: [PATCH V5 1/1] cpufreq: scmi: Register for limit change
 notifications

On Tue, Jun 04, 2024 at 12:56:54AM +0530, Sibi Sankar 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>
> ---
> 
> v5:
> * Drop patch 1 and use pm_qos to update constraints. [Vincent]
> * Use sdev instead of cpu_dev in dev_warn. [Christian]
> * Pass sdev directly through private data. [Christian]
> * Dropping Rb's for now.
> 
>  drivers/cpufreq/scmi-cpufreq.c | 36 ++++++++++++++++++++++++++++++++++
>  1 file changed, 36 insertions(+)

Tested-by: Mike Tipton <quic_mdtipton@...cinc.com>

> 
> diff --git a/drivers/cpufreq/scmi-cpufreq.c b/drivers/cpufreq/scmi-cpufreq.c
> index b87fd127aa43..0edfa55d8e49 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 (ret < 0)
> +		pr_warn("failed to update freq constraint: %d\n", ret);

This would be better as a dev_warn() with the cpu device. Other than
that, looks good to me.