amd-pstate Dynamic EPP and raw EPP

From: Mario Limonciello <[email protected]>

Dynamic energy performance preference will change the EPP profile based on whether the machine is running on AC or DC power.

A notification chain from the power supply core is used to adjust EPP values on plug in or plug out events.

For non-server systems:
* the default EPP for AC mode is performance.
* the default EPP for DC mode is balance_performance.

Signed-off-by Mario Limonciello <[email protected]>

drivers/cpufreq/amd-pstate.c +18 -0

+static int amd_pstate_set_dynamic_epp(struct cpufreq_policy *policy)
+{
+	struct amd_cpudata *cpudata = policy->driver_data;
+	int ret;
+	u8 epp;
+
+	epp = amd_pstate_get_balanced_epp(policy);
+	ret = amd_pstate_set_epp(policy, epp);
+	if (ret)
+		return ret;
+
+	/* only enable notifier if things will actually change */
+	if (cpudata->epp_default_ac != cpudata->epp_default_dc) {
+		ret = power_supply_reg_notifier(&cpudata->power_nb);
+		if (ret)
+			goto cleanup;
+		cpudata->power_nb.notifier_call = amd_pstate_power_supply_notifier;
+	}

+
/* Sysfs attributes */

static struct freq_attr *amd_pstate_attr[] = {

drivers/cpufreq/amd-pstate.c +1 -0

 	&amd_pstate_max_freq,

@@ -1421,6 +1528,7 @@ static struct freq_attr *amd_pstate_epp_attr[] = {
 static struct attribute *pstate_global_attributes[] = {
 	&dev_attr_status.attr,
 	&dev_attr_prefcore.attr,
+	&dev_attr_dynamic_epp.attr,
 	NULL
 };
 

From: Mario Limonciello <[email protected]>

Add amd_dynamic_epp=enable and amd_dynamic_epp=disable to override the kernel configuration option CONFIG_X86_AMD_PSTATE_DYNAMIC_EPP locally.

Signed-off-by Mario Limonciello <[email protected]>

---
 Documentation/admin-guide/kernel-parameters.txt |  7 +++++++
 Documentation/admin-guide/pm/amd-pstate.rst     |  7 +++++++
 drivers/cpufreq/amd-pstate.c                    | 11 +++++++++++
 3 files changed, 25 insertions(+)

Documentation/admin-guide/kernel-parameters.txt +7 -0

index a8d0afde7f85a..d7d547bbda430 100644
@@ -490,6 +490,13 @@ Kernel parameters
 			disable
 			  Disable amd-pstate preferred core.
 
+	amd_dynamic_epp=
+			[X86]
+			disable
+			  Disable amd-pstate dynamic EPP.
+			enable
+			  Enable amd-pstate dynamic EPP.
+
 	amijoy.map=	[HW,JOY] Amiga joystick support
 			Map of devices attached to JOY0DAT and JOY1DAT
 			Format: <a>,<b>

Documentation/admin-guide/pm/amd-pstate.rst +0 -0

index 5aa9fb77a078c..df4607b6a5f62 100644

Documentation/admin-guide/pm/amd-pstate.rst +1 -0

+
 User Space Interface in ``sysfs`` - General
 ===========================================
 

drivers/cpufreq/amd-pstate.c +11 -0

index 26a8552581c57..7dd50b5825d78 100644
@@ -1992,8 +1992,19 @@ static int __init amd_prefcore_param(char *str)
 	return 0;
 }
 
+static int __init amd_dynamic_epp_param(char *str)
+{
+	if (!strcmp(str, "disable"))
+		dynamic_epp = false;
+	if (!strcmp(str, "enable"))
+		dynamic_epp = true;
+
+	return 0;
+}
+
 early_param("amd_pstate", amd_pstate_param);
 early_param("amd_prefcore", amd_prefcore_param);
+early_param("amd_dynamic_epp", amd_dynamic_epp_param);
 
 MODULE_AUTHOR("Huang Rui <[email protected]>");
 MODULE_DESCRIPTION("AMD Processor P-state Frequency Driver");

Signature · 2 lines

-- 
2.43.0

From: Mario Limonciello <[email protected]>

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 <[email protected]>

---
 Documentation/admin-guide/pm/amd-pstate.rst |   4 +-
 drivers/cpufreq/Kconfig.x86                 |   1 +
 drivers/cpufreq/amd-pstate.c                | 144 +++++++++++++++++---
 drivers/cpufreq/amd-pstate.h                |  10 ++
 4 files changed, 141 insertions(+), 18 deletions(-)

Documentation/admin-guide/pm/amd-pstate.rst +3 -1

index df4607b6a5f62..a6745f2358e61 100644
@@ -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.
 

drivers/cpufreq/Kconfig.x86 +1 -0

index cdaa8d858045a..a0dbb9808ae99 100644
@@ -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

drivers/cpufreq/amd-pstate.c +127 -17

index 7dd50b5825d78..e1ccbbdd56d42 100644
@@ -109,6 +109,7 @@ static struct quirk_entry *quirks;
  *	2		balance_performance
  *	3		balance_power
  *	4		power
+ *	5		custom (for raw EPP values)
  */
 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,
 	EPP_INDEX_MAX,
 };
 

@@ -125,6 +127,7 @@ 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",
 };
 static_assert(ARRAY_SIZE(energy_perf_strings) == EPP_INDEX_MAX);
 

@@ -135,7 +138,7 @@ static unsigned int epp_values[] = {
 	[EPP_INDEX_BALANCE_POWERSAVE] = AMD_CPPC_EPP_BALANCE_POWERSAVE,
 	[EPP_INDEX_POWERSAVE] = AMD_CPPC_EPP_POWERSAVE,
 };
-static_assert(ARRAY_SIZE(epp_values) == EPP_INDEX_MAX);
+static_assert(ARRAY_SIZE(epp_values) == EPP_INDEX_MAX - 1);
 
 typedef int (*cppc_mode_transition_fn)(int);
 

@@ -1094,6 +1097,10 @@ 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);

@@ -1102,14 +1109,84 @@ 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);
+	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,
+};
+
+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;
 }
+EXPORT_SYMBOL_GPL(amd_pstate_clear_dynamic_epp);
 
 static int amd_pstate_set_dynamic_epp(struct cpufreq_policy *policy)
 {

@@ -1117,11 +1194,35 @@ static int amd_pstate_set_dynamic_epp(struct cpufreq_policy *policy)
 	int ret;
 	u8 epp;
 
-	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) {
 		ret = power_supply_reg_notifier(&cpudata->power_nb);

@@ -1227,8 +1328,8 @@ 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)
+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;

@@ -1239,16 +1340,22 @@ static ssize_t store_energy_performance_preference(
 		return -EBUSY;
 	}
 
-	ret = sysfs_match_string(energy_perf_strings, buf);
-	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(buf, 0, &epp);
+	if (ret) {
+		ret = sysfs_match_string(energy_perf_strings, buf);
+		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) {
 		pr_debug("EPP cannot be set under performance policy\n");
 		return -EBUSY;
 	}

@@ -1259,9 +1366,9 @@ 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;

@@ -1282,11 +1389,12 @@ 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)
 {

@@ -1621,10 +1729,12 @@ 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) {

drivers/cpufreq/amd-pstate.h +10 -0

index 7bfe5f8115623..9839c7c6558f4 100644
@@ -9,6 +9,7 @@
 #define _LINUX_AMD_PSTATE_H
 
 #include <linux/pm_qos.h>
+#include <linux/platform_profile.h>
 
 /*********************************************************************
  *                        AMD P-state INTERFACE                       *

@@ -110,6 +111,11 @@ 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;
 };
 
 /*

@@ -126,5 +132,9 @@ enum amd_pstate_mode {
 const char *amd_pstate_get_mode_string(enum amd_pstate_mode mode);
 int amd_pstate_get_status(void);
 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 */

Signature · 2 lines

-- 
2.43.0

From: Mario Limonciello <[email protected]>

The energy performance preference field of the CPPC request MSR supports values from 0 to 255, but the strings only offer 4 values.

The other values are useful for tuning the performance of some workloads.

Add support for writing the raw energy performance preference value to the sysfs file. If the last value written was an integer then an integer will be returned. If the last value written was a string then a string will be returned.

Signed-off-by Mario Limonciello <[email protected]>

---
 Documentation/admin-guide/pm/amd-pstate.rst | 16 +++++++++++-----
 drivers/cpufreq/amd-pstate.c                | 11 +++++++++--
 drivers/cpufreq/amd-pstate.h                |  1 +
 3 files changed, 21 insertions(+), 7 deletions(-)

Documentation/admin-guide/pm/amd-pstate.rst +11 -5

index a6745f2358e61..674e76ff9293e 100644
@@ -280,16 +280,22 @@ A list of all the supported EPP preferences that could be used for
 These profiles represent different hints that are provided
 to the low-level firmware about the user's desired energy vs efficiency
 tradeoff.  ``default`` represents the epp value is set by platform
-firmware. This attribute is read-only.
+firmware. ``custom`` designates that integer values 0-255 may be written
+as well.  This attribute is read-only.
 
 ``energy_performance_preference``
 
 The current energy performance preference can be read from this attribute.
 and user can change current preference according to energy or performance needs
-Please get all support profiles list from
-``energy_performance_available_preferences`` attribute, all the profiles are
-integer values defined between 0 to 255 when EPP feature is enabled by platform
-firmware, but if the dynamic EPP feature is enabled, driver will block writes.
+Coarse named profiles are available in the attribute
+``energy_performance_available_preferences``.
+Users can also write individual integer values between 0 to 255.
+When EPP feature is enabled by platform firmware but if the dynamic EPP feature is
+enabled, driver will ignore the written value. Lower epp values shift the bias
+towards improved performance while a higher epp value shifts the bias towards
+power-savings. The exact impact can change from one platform to the other.
+If a valid integer was last written, then a number will be returned on future reads.
+If a valid string was last written then a string will be returned on future reads.
 This attribute is read-write.
 
 ``boost``

drivers/cpufreq/amd-pstate.c +0 -0

index e1ccbbdd56d42..14347baf3cefb 100644

drivers/cpufreq/amd-pstate.c +8 -2

 	u8 epp;
 
 	if (cpudata->dynamic_epp) {

@@ -1345,6 +1346,7 @@ ssize_t store_energy_performance_preference(struct cpufreq_policy *policy,
 	 * matches an index in the energy_perf_strings array
 	 */
 	ret = kstrtou8(buf, 0, &epp);
+	raw_epp = !ret;
 	if (ret) {
 		ret = sysfs_match_string(energy_perf_strings, buf);
 		if (ret < 0 || ret == EPP_INDEX_CUSTOM)

@@ -1364,7 +1366,9 @@ ssize_t store_energy_performance_preference(struct cpufreq_policy *policy,
 	if (ret)
 		return ret;
 
-	return ret ? ret : count;
+	cpudata->raw_epp = raw_epp;
+
+	return count;
 }
 EXPORT_SYMBOL_GPL(store_energy_performance_preference);
 

@@ -1375,6 +1379,9 @@ ssize_t show_energy_performance_preference(struct cpufreq_policy *policy, char *
 
 	epp = FIELD_GET(AMD_CPPC_EPP_PERF_MASK, cpudata->cppc_req_cached);
 
+	if (cpudata->raw_epp)
+		return sysfs_emit(buf, "%u\n", epp);
+
 	switch (epp) {
 	case AMD_CPPC_EPP_PERFORMANCE:
 		preference = EPP_INDEX_PERFORMANCE;

@@ -1389,7 +1396,7 @@ ssize_t show_energy_performance_preference(struct cpufreq_policy *policy, char *
 		preference = EPP_INDEX_POWERSAVE;
 		break;
 	default:
-		return sysfs_emit(buf, "%u\n", epp);
+		return -EINVAL;
 	}
 
 	return sysfs_emit(buf, "%s\n", energy_perf_strings[preference]);

drivers/cpufreq/amd-pstate.h +0 -0

index 9839c7c6558f4..38b575b8ad959 100644

From: Mario Limonciello <[email protected]>

Ensure that all supported raw EPP values work properly.

Signed-off-by Mario Limonciello <[email protected]>

---
 drivers/cpufreq/amd-pstate-ut.c | 58 +++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)

drivers/cpufreq/amd-pstate-ut.c +43 -0

index 447b9aa5ce40b..d51233b753db6 100644
@@ -26,6 +26,7 @@
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/moduleparam.h>
+#include <linux/mm.h>
 #include <linux/fs.h>
 #include <linux/cleanup.h>
 

@@ -35,6 +36,7 @@
 
 #include "amd-pstate.h"
 
+DEFINE_FREE(cleanup_page, void *, if (_T) free_page((unsigned long)_T))
 
 struct amd_pstate_ut_struct {
 	const char *name;

@@ -48,6 +50,7 @@ static int amd_pstate_ut_acpi_cpc_valid(u32 index);
 static int amd_pstate_ut_check_enabled(u32 index);
 static int amd_pstate_ut_check_perf(u32 index);
 static int amd_pstate_ut_check_freq(u32 index);
+static int amd_pstate_ut_epp(u32 index);
 static int amd_pstate_ut_check_driver(u32 index);
 
 static struct amd_pstate_ut_struct amd_pstate_ut_cases[] = {

@@ -55,6 +58,7 @@ static struct amd_pstate_ut_struct amd_pstate_ut_cases[] = {
 	{"amd_pstate_ut_check_enabled",    amd_pstate_ut_check_enabled    },
 	{"amd_pstate_ut_check_perf",       amd_pstate_ut_check_perf       },
 	{"amd_pstate_ut_check_freq",       amd_pstate_ut_check_freq       },
+	{"amd_pstate_ut_epp",              amd_pstate_ut_epp              },
 	{"amd_pstate_ut_check_driver",	   amd_pstate_ut_check_driver     }
 };
 

@@ -241,6 +245,60 @@ static int amd_pstate_set_mode(enum amd_pstate_mode mode)
 	return amd_pstate_update_status(mode_str, strlen(mode_str));
 }
 
+static int amd_pstate_ut_epp(u32 index)
+{
+	struct cpufreq_policy *policy __free(put_cpufreq_policy) = NULL;
+	void *buf __free(cleanup_page) = NULL;
+	struct amd_cpudata *cpudata;
+	int ret, cpu = 0;
+	u16 epp;
+
+	policy = cpufreq_cpu_get(cpu);
+	if (!policy)
+		return -ENODEV;
+
+	cpudata = policy->driver_data;
+
+	/* disable dynamic EPP before running test */
+	if (cpudata->dynamic_epp) {
+		pr_debug("Dynamic EPP is enabled, disabling it\n");
+		amd_pstate_clear_dynamic_epp(policy);
+	}
+
+	buf = (void *)__get_free_page(GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	ret = amd_pstate_set_mode(AMD_PSTATE_ACTIVE);
+	if (ret)
+		return ret;
+
+	for (epp = 0; epp <= U8_MAX; epp++) {
+		u8 val;
+
+		/* write all EPP values */
+		memset(buf, 0, sizeof(*buf));
+		snprintf(buf, PAGE_SIZE, "%d", epp);
+		ret = store_energy_performance_preference(policy, buf, sizeof(*buf));
+		if (ret < 0)
+			return ret;
+
+		/* check if the EPP value reads back correctly for raw numbers */

drivers/cpufreq/amd-pstate-ut.c +4 -0

+
+	return 0;
+}
+
 static int amd_pstate_ut_check_driver(u32 index)
 {
 	enum amd_pstate_mode mode1, mode2 = AMD_PSTATE_DISABLE;

Signature · 2 lines

-- 
2.43.0

Dynamic EPP allows the kernel to register amd-pstate as part of a platform profile. It will change EPP modes matching the user's preference to the platform profile sysfs files as well as power adapter state.

Raw EPP allows userspace to write integers to
energy_performance_preference.

v4: https://lore.kernel.org/linux-pm/[email protected]/
Mario Limonciello (5):
cpufreq/amd-pstate: Add dynamic energy performance preference cpufreq/amd-pstate: add kernel command line to override dynamic epp cpufreq/amd-pstate: Add support for platform profile class cpufreq/amd-pstate: Add support for raw EPP writes cpufreq/amd-pstate-ut: Add a unit test for raw EPP

  .../admin-guide/kernel-parameters.txt         |   7 +
  Documentation/admin-guide/pm/amd-pstate.rst   |  41 ++-
  drivers/cpufreq/Kconfig.x86                   |  13 +
  drivers/cpufreq/amd-pstate-ut.c               |  58 ++++
  drivers/cpufreq/amd-pstate.c                  | 283 ++++++++++++++++--
  drivers/cpufreq/amd-pstate.h                  |  16 +-
  6 files changed, 394 insertions(+), 24 deletions(-)