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SubjectRe: [PATCH v3 7/8] cpufreq: amd-pstate: add frequency dynamic boost sysfs control
From
+wyes.karny@amd.com

On 11/7/2022 11:57, Perry Yuan wrote:
> 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@amd.com>
> ---
> drivers/cpufreq/amd-pstate.c | 53 ++++++++++++++++++++++++++++++++++++
> 1 file changed, 53 insertions(+)

Make sure that you update the documentation for this new sysfs file as well.

>
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 841b1e2383b8..6958c5fd9e1c 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -786,12 +786,46 @@ static ssize_t show_energy_performance_preference(
> return sprintf(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_pstate_dynamic_boost(struct kobject *kobj,
> + struct kobj_attribute *attr, char *buf)
> +{
> + return sprintf(buf, "%u\n", cppc_boost);
> +}
> +
> +static ssize_t store_pstate_dynamic_boost(struct kobject *a,
> + struct kobj_attribute *b,
> + const char *buf, size_t count)
> +{
> + unsigned int input;
> + int ret;
> +
> + ret = kstrtouint(buf, 10, &input);
> + if (ret)
> + return ret;

To be more flexible maybe kstrtobool would be better here instead?

> +
> + mutex_lock(&amd_pstate_driver_lock);
> + cppc_boost = !!input;
> + 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(pstate_dynamic_boost);
>
> static struct freq_attr *amd_pstate_attr[] = {
> &amd_pstate_max_freq,
> @@ -809,6 +843,15 @@ static struct freq_attr *amd_pstate_epp_attr[] = {
> NULL,
> };
>
> +static struct attribute *pstate_global_attributes[] = {
> + &pstate_dynamic_boost.attr,
> + 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;
> @@ -1416,6 +1459,16 @@ static int __init amd_pstate_init(void)
> pr_err("failed to register amd pstate driver with return %d\n",
> ret);
>
> + amd_pstate_kobj = kobject_create_and_add("amd-pstate", &cpu_subsys.dev_root->kobj);
> + if (!amd_pstate_kobj)
> + pr_err("amd-pstate: Global sysfs registration failed.\n");
> +
> + ret = sysfs_create_group(amd_pstate_kobj, &amd_pstate_global_attr_group);
> + if (ret) {
> + pr_err("amd-pstate: Sysfs attribute export failed with error %d.\n",
> + ret);

amd-pstate can currently be a module too. So don't you need the
matching cleanup path for this code too?

Also, regarding the error messages you don't need to prefix with
"amd-pstate: ", amd-pstate.c already sets `pr_fmt`.

> + }
> +
> return ret;
> }
> device_initcall(amd_pstate_init);

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