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Message-ID: <08e3b020-ea5a-4ba1-b817-0746a277669f@amd.com>
Date: Mon, 24 Mar 2025 16:00:51 +0530
From: Dhananjay Ugwekar <Dhananjay.Ugwekar@....com>
To: Mario Limonciello <superm1@...nel.org>,
 "Gautham R . Shenoy" <gautham.shenoy@....com>,
 Perry Yuan <perry.yuan@....com>
Cc: "open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
 <linux-kernel@...r.kernel.org>,
 "open list:CPU FREQUENCY SCALING FRAMEWORK" <linux-pm@...r.kernel.org>,
 Mario Limonciello <mario.limonciello@....com>
Subject: Re: [PATCH v4 3/5] cpufreq/amd-pstate: Add support for platform
 profile class

On 3/21/2025 7:58 AM, Mario Limonciello wrote:
> From: Mario Limonciello <mario.limonciello@....com>
> 
> 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.
> 
> Signed-off-by: Mario Limonciello <mario.limonciello@....com>
> ---
>  Documentation/admin-guide/pm/amd-pstate.rst |   4 +-
>  drivers/cpufreq/Kconfig.x86                 |   1 +
>  drivers/cpufreq/amd-pstate.c                | 142 +++++++++++++++++---
>  drivers/cpufreq/amd-pstate.h                |  10 ++
>  4 files changed, 140 insertions(+), 17 deletions(-)
> 
> diff --git a/Documentation/admin-guide/pm/amd-pstate.rst b/Documentation/admin-guide/pm/amd-pstate.rst
> index 8424e7119dd7e..36950fb6568c0 100644
> --- a/Documentation/admin-guide/pm/amd-pstate.rst
> +++ b/Documentation/admin-guide/pm/amd-pstate.rst
> @@ -321,7 +321,9 @@ 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 3a8bdc35f488a..8fc8319861bdf 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 8172bd4b5952f..2a62b12148544 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -109,6 +109,7 @@ static struct quirk_entry *quirks;
>   *	2		balance_performance
>   *	3		balance_power
>   *	4		power
> + *	5		custom (for raw EPP values)

Should we move these "custom" changes to the raw EPP patch ?

>   */
>  enum energy_perf_value_index {
>  	EPP_INDEX_DEFAULT = 0,
> @@ -116,6 +117,7 @@ enum energy_perf_value_index {
>  	EPP_INDEX_BALANCE_PERFORMANCE,
>  	EPP_INDEX_BALANCE_POWERSAVE,
>  	EPP_INDEX_POWERSAVE,
> +	EPP_INDEX_CUSTOM,
>  };
>  
>  static const char * const energy_perf_strings[] = {
> @@ -124,6 +126,7 @@ static const char * const energy_perf_strings[] = {
>  	[EPP_INDEX_BALANCE_PERFORMANCE] = "balance_performance",
>  	[EPP_INDEX_BALANCE_POWERSAVE] = "balance_power",
>  	[EPP_INDEX_POWERSAVE] = "power",
> +	[EPP_INDEX_CUSTOM] = "custom",
>  	NULL
>  };
>  
> @@ -1077,6 +1080,10 @@ 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);
> @@ -1085,14 +1092,84 @@ static int amd_pstate_power_supply_notifier(struct notifier_block *nb,
>  
>  	return NOTIFY_OK;
>  }
> -static void amd_pstate_clear_dynamic_epp(struct cpufreq_policy *policy)
> +
> +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);

We should add "if (!policy)" check here?

> +	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;
> +}
> +
[snip]
> @@ -1228,16 +1329,22 @@ static ssize_t store_energy_performance_preference(
>  	if (ret != 1)
>  		return -EINVAL;
>  
> -	ret = match_string(energy_perf_strings, -1, str_preference);
> -	if (ret < 0)
> -		return -EINVAL;
> -
> -	if (ret)
> -		epp = epp_values[ret];
> -	else
> -		epp = amd_pstate_get_balanced_epp(policy);
> +	/*
> +	 * if the value matches a number, use that, otherwise see if
> +	 * matches an index in the energy_perf_strings array
> +	 */
> +	ret = kstrtou8(str_preference, 0, &epp);
> +	if (ret) {
> +		ret = match_string(energy_perf_strings, -1, str_preference);
> +		if (ret < 0 || ret == EPP_INDEX_CUSTOM)
> +			return -EINVAL;
> +		if (ret)
> +			epp = epp_values[ret];
> +		else
> +			epp = amd_pstate_get_balanced_epp(policy);
> +	}
>  
> -	if (epp > 0 && policy->policy == CPUFREQ_POLICY_PERFORMANCE) {
> +	if (epp > 0 && cpudata->policy == CPUFREQ_POLICY_PERFORMANCE) {
		       ^^^^^^^ this change wont make any difference right?	

>  		pr_debug("EPP cannot be set under performance policy\n");
>  		return -EBUSY;
>  	}
> @@ -1248,9 +1355,9 @@ static ssize_t store_energy_performance_preference(
>  
>  	return ret ? ret : count;
>  }
> +EXPORT_SYMBOL_GPL(store_energy_performance_preference);
>  
> -static ssize_t show_energy_performance_preference(
> -				struct cpufreq_policy *policy, char *buf)
> +ssize_t show_energy_performance_preference(struct cpufreq_policy *policy, char *buf)
>  {
>  	struct amd_cpudata *cpudata = policy->driver_data;
>  	u8 preference, epp;
> @@ -1271,11 +1378,12 @@ static ssize_t show_energy_performance_preference(
>  		preference = EPP_INDEX_POWERSAVE;
>  		break;
>  	default:
> -		return -EINVAL;
> +		return sysfs_emit(buf, "%u\n", epp);
>  	}
>  
>  	return sysfs_emit(buf, "%s\n", energy_perf_strings[preference]);
>  }
> +EXPORT_SYMBOL_GPL(show_energy_performance_preference);
>  
>  static void amd_pstate_driver_cleanup(void)
>  {
> @@ -1599,10 +1707,12 @@ 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);

Why dont we just set the defaults to "AMD_CPPC_EPP_BALANCE_PERFORMANCE" for server systems, so 
that the governor, profile and the EPP values are aligned at initialization. Any historical 
context for using amd_pstate_get_epp() to init the default epp value?, do we want to preserve 
the initial value set by the SMU?

> +		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 (cpu_feature_enabled(X86_FEATURE_CPPC)) {
> diff --git a/drivers/cpufreq/amd-pstate.h b/drivers/cpufreq/amd-pstate.h
> index 6882876f895de..b4c5374762110 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                       *
> @@ -108,6 +109,11 @@ 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;
>  };
>  
>  /*
> @@ -123,5 +129,9 @@ enum amd_pstate_mode {
>  };
>  const char *amd_pstate_get_mode_string(enum amd_pstate_mode mode);
>  int amd_pstate_update_status(const char *buf, size_t size);
> +ssize_t store_energy_performance_preference(struct cpufreq_policy *policy,
> +					    const char *buf, size_t count);
> +ssize_t show_energy_performance_preference(struct cpufreq_policy *policy, char *buf);
> +void amd_pstate_clear_dynamic_epp(struct cpufreq_policy *policy);
>  
>  #endif /* _LINUX_AMD_PSTATE_H */


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