Re: [PATCH v9 09/13] cpufreq: amd-pstate: add driver working mode switch support

Wyes Karny
2023-01-06T03:46:23Z

Hi Perry,

On 12/25/2022 10:04 PM, Perry Yuan wrote:
----------------------------------->8----------------------------------
> +static int amd_pstate_update_status(const char *buf, size_t size)
> +{
> + int ret;
> + int mode_idx;
> +
> + if (size > 7 || size < 3)
> + return -EINVAL;
> + mode_idx = get_mode_idx_from_str(buf, size);
> +
> + switch(mode_idx) {
> + case AMD_PSTATE_DISABLE:
> + if (!default_pstate_driver)
> + return -EINVAL;
> + if (cppc_state == AMD_PSTATE_ACTIVE)
> + return -EBUSY;

what's the reason for not supporting active -> disable?

> + ret = cpufreq_unregister_driver(default_pstate_driver);
> + amd_pstate_driver_cleanup();
> + break;
> + case AMD_PSTATE_PASSIVE:
> + if (default_pstate_driver) {
> + if (default_pstate_driver == &amd_pstate_driver)
> + return 0;
> + cpufreq_unregister_driver(default_pstate_driver);
> + cppc_state = AMD_PSTATE_PASSIVE;
> + default_pstate_driver = &amd_pstate_driver;
> + }
> +
> + ret = cpufreq_register_driver(default_pstate_driver);
> + break;
> + case AMD_PSTATE_ACTIVE:
> + if (default_pstate_driver) {
> + if (default_pstate_driver == &amd_pstate_epp_driver)
> + return 0;
> + cpufreq_unregister_driver(default_pstate_driver);
> + default_pstate_driver = &amd_pstate_epp_driver;
> + cppc_state = AMD_PSTATE_ACTIVE;
> + }
> +
> + ret = cpufreq_register_driver(default_pstate_driver);
> + break;
> + default:
> + break;
> + ret = -EINVAL;
> + }
> +
> + return ret;
> +}
> +
> +static ssize_t show_status(struct kobject *kobj,
> + struct kobj_attribute *attr, char *buf)
> +{
> + ssize_t ret;
> +
> + mutex_lock(&amd_pstate_driver_lock);
> + ret = amd_pstate_show_status(buf);
> + mutex_unlock(&amd_pstate_driver_lock);
> +
> + return ret;
> +}
> +
> +static ssize_t store_status(struct kobject *a, struct kobj_attribute *b,
> + const char *buf, size_t count)
> +{
> + char *p = memchr(buf, '\n', count);
> + int ret;
> +
> + mutex_lock(&amd_pstate_driver_lock);
> + ret = amd_pstate_update_status(buf, p ? p - buf : count);
> + mutex_unlock(&amd_pstate_driver_lock);
> +
> + return ret < 0 ? ret : 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(status);
>
> static struct freq_attr *amd_pstate_attr[] = {
> &amd_pstate_max_freq,
> @@ -795,6 +885,15 @@ static struct freq_attr *amd_pstate_epp_attr[] = {
> NULL,
> };
>
> +static struct attribute *pstate_global_attributes[] = {
> + &status.attr,
> + NULL
> +};
> +
> +static const struct attribute_group amd_pstate_global_attr_group = {
> + .attrs = pstate_global_attributes,
> +};
> +
> static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
> {
> int min_freq, max_freq, nominal_freq, lowest_nonlinear_freq, ret;
> @@ -1154,6 +1253,25 @@ static int __init amd_pstate_init(void)
> if (ret)
> pr_err("failed to register 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:
> + cpufreq_unregister_driver(default_pstate_driver);
> return ret;
> }
> device_initcall(amd_pstate_init);

--
Thanks & Regards,
Wyes