Re: [PATCH v6 3/5] cpufreq/amd-pstate: Add support for platform profile class

[Gautham R. Shenoy]

On Sun, Mar 29, 2026 at 03:38:09PM -0500, Mario Limonciello (AMD) wrote:
> The platform profile core allows multiple drivers and devices to
> register platform profile support.
> 
> When the legacy platform profile interface is used all drivers will
> adjust the platform profile as well.
> 
> Add support for registering every CPU with the platform profile handler
> when dynamic EPP is enabled.
> 
> The end result will be that changing the platform profile will modify
> EPP accordingly.

This looks good to me.

Reviewed-by: Gautham R. Shenoy <gautham.shenoy@xxxxxxx>

-- 
Thanks and Regards
gautham.

> 
> Signed-off-by: Mario Limonciello (AMD) <superm1@xxxxxxxxxx>
> ---
> v5->v6:
>  * Keep the platform profile patch focused on platform profile support
>  * Move the raw EPP plumbing into the follow-up raw EPP patch
>  * Move the test helper exports into the unit-test patch
> ---
>  Documentation/admin-guide/pm/amd-pstate.rst |   4 +-
>  drivers/cpufreq/Kconfig.x86                 |   1 +
>  drivers/cpufreq/amd-pstate.c                | 110 ++++++++++++++++++--
>  drivers/cpufreq/amd-pstate.h                |   6 ++
>  4 files changed, 114 insertions(+), 7 deletions(-)
> 
> diff --git a/Documentation/admin-guide/pm/amd-pstate.rst b/Documentation/admin-guide/pm/amd-pstate.rst
> index 210207d301aa5..2d92c8072b83c 100644
> --- a/Documentation/admin-guide/pm/amd-pstate.rst
> +++ b/Documentation/admin-guide/pm/amd-pstate.rst
> @@ -357,7 +357,9 @@ Whether this behavior is enabled by default with the kernel config option
>  at runtime by the sysfs file ``/sys/devices/system/cpu/cpufreq/policyX/dynamic_epp``.
>  
>  When set to enabled, the driver will select a different energy performance
> -profile when the machine is running on battery or AC power.
> +profile when the machine is running on battery or AC power. The driver will
> +also register with the platform profile handler to receive notifications of
> +user desired power state and react to those.
>  When set to disabled, the driver will not change the energy performance profile
>  based on the power source and will not react to user desired power state.
>  
> diff --git a/drivers/cpufreq/Kconfig.x86 b/drivers/cpufreq/Kconfig.x86
> index cdaa8d858045a..a0dbb9808ae99 100644
> --- a/drivers/cpufreq/Kconfig.x86
> +++ b/drivers/cpufreq/Kconfig.x86
> @@ -40,6 +40,7 @@ config X86_AMD_PSTATE
>  	select ACPI_PROCESSOR
>  	select ACPI_CPPC_LIB if X86_64
>  	select CPU_FREQ_GOV_SCHEDUTIL if SMP
> +	select ACPI_PLATFORM_PROFILE
>  	help
>  	  This driver adds a CPUFreq driver which utilizes a fine grain
>  	  processor performance frequency control range instead of legacy
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index e96f1da5c7b38..93cda05ffa855 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -1182,6 +1182,10 @@ static int amd_pstate_power_supply_notifier(struct notifier_block *nb,
>  	if (event != PSY_EVENT_PROP_CHANGED)
>  		return NOTIFY_OK;
>  
> +	/* dynamic actions are only applied while platform profile is in balanced */
> +	if (cpudata->current_profile != PLATFORM_PROFILE_BALANCED)
> +		return 0;
> +
>  	epp = amd_pstate_get_balanced_epp(policy);
>  
>  	ret = amd_pstate_set_epp(policy, epp);
> @@ -1190,12 +1194,81 @@ static int amd_pstate_power_supply_notifier(struct notifier_block *nb,
>  
>  	return NOTIFY_OK;
>  }
> +
> +static int amd_pstate_profile_probe(void *drvdata, unsigned long *choices)
> +{
> +	set_bit(PLATFORM_PROFILE_LOW_POWER, choices);
> +	set_bit(PLATFORM_PROFILE_BALANCED, choices);
> +	set_bit(PLATFORM_PROFILE_PERFORMANCE, choices);
> +
> +	return 0;
> +}
> +
> +static int amd_pstate_profile_get(struct device *dev,
> +				  enum platform_profile_option *profile)
> +{
> +	struct amd_cpudata *cpudata = dev_get_drvdata(dev);
> +
> +	*profile = cpudata->current_profile;
> +
> +	return 0;
> +}
> +
> +static int amd_pstate_profile_set(struct device *dev,
> +				  enum platform_profile_option profile)
> +{
> +	struct amd_cpudata *cpudata = dev_get_drvdata(dev);
> +	struct cpufreq_policy *policy __free(put_cpufreq_policy) = cpufreq_cpu_get(cpudata->cpu);
> +	int ret;
> +
> +	switch (profile) {
> +	case PLATFORM_PROFILE_LOW_POWER:
> +		if (cpudata->policy != CPUFREQ_POLICY_POWERSAVE)
> +			cpudata->policy = CPUFREQ_POLICY_POWERSAVE;
> +		ret = amd_pstate_set_epp(policy, AMD_CPPC_EPP_POWERSAVE);
> +		if (ret)
> +			return ret;
> +		break;
> +	case PLATFORM_PROFILE_BALANCED:
> +		if (cpudata->policy != CPUFREQ_POLICY_POWERSAVE)
> +			cpudata->policy = CPUFREQ_POLICY_POWERSAVE;
> +		ret = amd_pstate_set_epp(policy,
> +					 amd_pstate_get_balanced_epp(policy));
> +		if (ret)
> +			return ret;
> +		break;
> +	case PLATFORM_PROFILE_PERFORMANCE:
> +		ret = amd_pstate_set_epp(policy, AMD_CPPC_EPP_PERFORMANCE);
> +		if (ret)
> +			return ret;
> +		break;
> +	default:
> +		pr_err("Unknown Platform Profile %d\n", profile);
> +		return -EOPNOTSUPP;
> +	}
> +
> +	cpudata->current_profile = profile;
> +
> +	return 0;
> +}
> +
> +static const struct platform_profile_ops amd_pstate_profile_ops = {
> +	.probe = amd_pstate_profile_probe,
> +	.profile_set = amd_pstate_profile_set,
> +	.profile_get = amd_pstate_profile_get,
> +};
> +
>  static void amd_pstate_clear_dynamic_epp(struct cpufreq_policy *policy)
>  {
>  	struct amd_cpudata *cpudata = policy->driver_data;
>  
>  	if (cpudata->power_nb.notifier_call)
>  		power_supply_unreg_notifier(&cpudata->power_nb);
> +	if (cpudata->ppdev) {
> +		platform_profile_remove(cpudata->ppdev);
> +		cpudata->ppdev = NULL;
> +	}
> +	kfree(cpudata->profile_name);
>  	cpudata->dynamic_epp = false;
>  }
>  
> @@ -1206,11 +1279,35 @@ static int amd_pstate_set_dynamic_epp(struct cpufreq_policy *policy)
>  	u8 epp;
>  
>  	policy->policy = CPUFREQ_POLICY_PERFORMANCE;
> -	epp = amd_pstate_get_balanced_epp(policy);
> +	switch (cpudata->current_profile) {
> +	case PLATFORM_PROFILE_PERFORMANCE:
> +		epp = AMD_CPPC_EPP_PERFORMANCE;
> +		break;
> +	case PLATFORM_PROFILE_LOW_POWER:
> +		epp = AMD_CPPC_EPP_POWERSAVE;
> +		break;
> +	case PLATFORM_PROFILE_BALANCED:
> +		epp = amd_pstate_get_balanced_epp(policy);
> +		break;
> +	default:
> +		pr_err("Unknown Platform Profile %d\n", cpudata->current_profile);
> +		return -EOPNOTSUPP;
> +	}
>  	ret = amd_pstate_set_epp(policy, epp);
>  	if (ret)
>  		return ret;
>  
> +	cpudata->profile_name = kasprintf(GFP_KERNEL, "amd-pstate-epp-cpu%d", cpudata->cpu);
> +
> +	cpudata->ppdev = platform_profile_register(get_cpu_device(policy->cpu),
> +						   cpudata->profile_name,
> +						   policy->driver_data,
> +						   &amd_pstate_profile_ops);
> +	if (IS_ERR(cpudata->ppdev)) {
> +		ret = PTR_ERR(cpudata->ppdev);
> +		goto cleanup;
> +	}
> +
>  	/* only enable notifier if things will actually change */
>  	if (cpudata->epp_default_ac != cpudata->epp_default_dc) {
>  		cpudata->power_nb.notifier_call = amd_pstate_power_supply_notifier;
> @@ -1311,8 +1408,8 @@ static ssize_t show_energy_performance_available_preferences(
>  	return offset;
>  }
>  
> -static ssize_t store_energy_performance_preference(
> -		struct cpufreq_policy *policy, const char *buf, size_t count)
> +static ssize_t store_energy_performance_preference(struct cpufreq_policy *policy,
> +					   const char *buf, size_t count)
>  {
>  	struct amd_cpudata *cpudata = policy->driver_data;
>  	ssize_t ret;
> @@ -1332,7 +1429,7 @@ static ssize_t store_energy_performance_preference(
>  	else
>  		epp = amd_pstate_get_balanced_epp(policy);
>  
> -	if (epp > 0 && policy->policy == CPUFREQ_POLICY_PERFORMANCE) {
> +	if (epp > 0 && cpudata->policy == CPUFREQ_POLICY_PERFORMANCE) {
>  		pr_debug("EPP cannot be set under performance policy\n");
>  		return -EBUSY;
>  	}
> @@ -1344,8 +1441,7 @@ static ssize_t store_energy_performance_preference(
>  	return ret ? ret : count;
>  }
>  
> -static ssize_t show_energy_performance_preference(
> -				struct cpufreq_policy *policy, char *buf)
> +static ssize_t show_energy_performance_preference(struct cpufreq_policy *policy, char *buf)
>  {
>  	struct amd_cpudata *cpudata = policy->driver_data;
>  	u8 preference, epp;
> @@ -1825,10 +1921,12 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy)
>  	    amd_pstate_acpi_pm_profile_undefined()) {
>  		policy->policy = CPUFREQ_POLICY_PERFORMANCE;
>  		cpudata->epp_default_ac = cpudata->epp_default_dc = amd_pstate_get_epp(cpudata);
> +		cpudata->current_profile = PLATFORM_PROFILE_PERFORMANCE;
>  	} else {
>  		policy->policy = CPUFREQ_POLICY_POWERSAVE;
>  		cpudata->epp_default_ac = AMD_CPPC_EPP_PERFORMANCE;
>  		cpudata->epp_default_dc = AMD_CPPC_EPP_BALANCE_PERFORMANCE;
> +		cpudata->current_profile = PLATFORM_PROFILE_BALANCED;
>  	}
>  
>  	if (dynamic_epp)
> diff --git a/drivers/cpufreq/amd-pstate.h b/drivers/cpufreq/amd-pstate.h
> index d929ae3163b3d..a7e52f79a8029 100644
> --- a/drivers/cpufreq/amd-pstate.h
> +++ b/drivers/cpufreq/amd-pstate.h
> @@ -9,6 +9,7 @@
>  #define _LINUX_AMD_PSTATE_H
>  
>  #include <linux/pm_qos.h>
> +#include <linux/platform_profile.h>
>  
>  /*********************************************************************
>   *                        AMD P-state INTERFACE                       *
> @@ -127,6 +128,11 @@ struct amd_cpudata {
>  	u8	epp_default_dc;
>  	bool	dynamic_epp;
>  	struct notifier_block power_nb;
> +
> +	/* platform profile */
> +	enum platform_profile_option current_profile;
> +	struct device *ppdev;
> +	char *profile_name;
>  };
>  
>  /*
> -- 
> 2.43.0
>