linux-kernel - Re: [PATCH v6 07/11] cpufreq: amd-pstate: add frequency dynamic boost sysfs control

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Date:   Fri, 2 Dec 2022 09:59:35 -0600
From:   "Limonciello, Mario" <mario.limonciello@....com>
To:     Perry Yuan <perry.yuan@....com>, rafael.j.wysocki@...el.com,
        ray.huang@....com, viresh.kumar@...aro.org
Cc:     Deepak.Sharma@....com, Nathan.Fontenot@....com,
        Alexander.Deucher@....com, Shimmer.Huang@....com,
        Xiaojian.Du@....com, Li.Meng@....com, wyes.karny@....com,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 07/11] cpufreq: amd-pstate: add frequency dynamic boost
 sysfs control

On 12/2/2022 01:47, Perry Yuan wrote:
> From: Perry Yuan <Perry.Yuan@....com>
> 
> Add one sysfs entry to control the CPU cores frequency boost state
> The attribute file can allow user to set max performance boosted or
> keeping at normal perf level.
> 
> Signed-off-by: Perry Yuan <Perry.Yuan@....com>
> ---
>   drivers/cpufreq/amd-pstate.c | 66 ++++++++++++++++++++++++++++++++++--
>   1 file changed, 64 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index b3a82cee2e83..6936df6e8642 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -774,12 +774,46 @@ static ssize_t show_energy_performance_preference(
>   	return  sysfs_emit(buf, "%s\n", energy_perf_strings[preference]);
>   }
>   
> +static void amd_pstate_update_policies(void)
> +{
> +	int cpu;
> +
> +	for_each_possible_cpu(cpu)
> +		cpufreq_update_policy(cpu);
> +}
> +
> +static ssize_t show_boost(struct kobject *kobj,
> +				struct kobj_attribute *attr, char *buf)
> +{
> +	return sysfs_emit(buf, "%u\n", cppc_boost);
> +}
> +
> +static ssize_t store_boost(struct kobject *a,
> +				       struct kobj_attribute *b,
> +				       const char *buf, size_t count)
> +{
> +	bool new_state;
> +	int ret;
> +
> +	ret = kstrtobool(buf, &new_state);
> +	if (ret)
> +		return -EINVAL;
> +
> +	mutex_lock(&amd_pstate_driver_lock);
> +	cppc_boost = !!new_state;
> +	amd_pstate_update_policies();
> +	mutex_unlock(&amd_pstate_driver_lock);
> +
> +	return count;
> +}
> +
>   cpufreq_freq_attr_ro(amd_pstate_max_freq);
>   cpufreq_freq_attr_ro(amd_pstate_lowest_nonlinear_freq);
>   
>   cpufreq_freq_attr_ro(amd_pstate_highest_perf);
>   cpufreq_freq_attr_rw(energy_performance_preference);
>   cpufreq_freq_attr_ro(energy_performance_available_preferences);
> +define_one_global_rw(boost);
>   
>   static struct freq_attr *amd_pstate_attr[] = {
>   	&amd_pstate_max_freq,
> @@ -797,6 +831,15 @@ static struct freq_attr *amd_pstate_epp_attr[] = {
>   	NULL,
>   };
>   
> +static struct attribute *pstate_global_attributes[] = {
> +	&boost.attr,

Make sure you update the documentation for the new sysfs attribute.

> +	NULL
> +};
> +
> +static const struct attribute_group amd_pstate_global_attr_group = {
> +	.attrs = pstate_global_attributes,
> +};
> +
>   static inline void update_boost_state(void)
>   {
>   	u64 misc_en;
> @@ -1415,9 +1458,28 @@ static int __init amd_pstate_init(void)
>   
>   	ret = cpufreq_register_driver(default_pstate_driver);
>   	if (ret)
> -		pr_err("failed to register amd pstate driver with return %d\n",
> -		       ret);
> +		pr_err("failed to register driver with return %d\n", ret);
> +
> +	amd_pstate_kobj = kobject_create_and_add("amd-pstate", &cpu_subsys.dev_root->kobj);
> +	if (!amd_pstate_kobj) {
> +		ret = -EINVAL;
> +		pr_err("global sysfs registration failed.\n");
> +		goto kobject_free;
> +	}
> +
> +	ret = sysfs_create_group(amd_pstate_kobj, &amd_pstate_global_attr_group);
> +	if (ret) {
> +		pr_err("sysfs attribute export failed with error %d.\n", ret);
> +		goto global_attr_free;
> +	}
> +
> +	return ret;
>   
> +global_attr_free:
> +	kobject_put(amd_pstate_kobj);
> +kobject_free:
> +	kfree(cpudata);
> +	cpufreq_unregister_driver(default_pstate_driver);
>   	return ret;
>   }
>   device_initcall(amd_pstate_init);