From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 73CE5387354; Sun, 29 Mar 2026 20:38:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774816705; cv=none; b=FBQcOoFdRerDDVhgmJwXx3KkXvZzAdcwdrIU8XhmCPA6Ld8T23+jHWsvKyKXQAMNmLKrvc7zUqrLBry5UN9193YiLScqYKJW0Uv0+9IxRp1mOFdCvmL/OYxI73gy51LbTTkmmF3jwMqui0sU6UexIScfMrv9cIIqjyiIOBH2Xpk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774816705; c=relaxed/simple; bh=GCDcQLs0jsdAuh+3LifhC5fa5TSYaqzut23mEb80PrQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=XfUa52NSkDfbFLuQC6XIoMMvmhcYvMyQKYIQ4nfwNqTbH1bi+/FBozFGDLTXHzYqxjVMkMng7ZE1D8QMBwQ4G2DlINLRO1Evimb6D952OdepREFsKsbJ8DW6yQSe2IelaMXOQKbFbLghkU/3ZXo6R6fcUWcC9ktwS0P2TkxO7yg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=NjAC4INF; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="NjAC4INF" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9E261C2BCB1; Sun, 29 Mar 2026 20:38:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1774816705; bh=GCDcQLs0jsdAuh+3LifhC5fa5TSYaqzut23mEb80PrQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=NjAC4INFHJbkX5BpEY970zkR9OPJUdfYK0c2Au5sj2X41ydmpei2QGyGIDdxuAc2e eh/E7TfvaTEAVKKgPyJ22fjKjsoNtIVuz4aSzPAWHvsWRY3qWLpprN2hgKUDn1h0r7 JQux6tfXxUxGZIyxts5mHJBXwOGuNvGlOeonTepTEi+4jQiNPnX3e1qStc1QxV5l9c gzIFQ1Yly9jtcHIaKtbLxO+TTu5xJsu/zUC5GFtlCuEp4523AdR/Lsr9NpB50vloD+ vWBnjCO+Uh+4cAfCcOi1LAC0NMrImlcnzrq6O0yN7RImReapL9leapu/WXW3mtz0wJ HuKk1sGKy87Bg== From: "Mario Limonciello (AMD)" To: "Gautham R . Shenoy" Cc: Perry Yuan , linux-kernel@vger.kernel.org (open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)), linux-pm@vger.kernel.org (open list:CPU FREQUENCY SCALING FRAMEWORK), "Mario Limonciello (AMD)" Subject: [PATCH v6 1/5] cpufreq/amd-pstate: Add dynamic energy performance preference Date: Sun, 29 Mar 2026 15:38:07 -0500 Message-ID: <20260329203811.2590633-2-superm1@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260329203811.2590633-1-superm1@kernel.org> References: <20260329203811.2590633-1-superm1@kernel.org> Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Dynamic energy performance preference changes 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. When enabled, the driver exposes a sysfs toggle for dynamic EPP, blocks manual writes to energy_performance_preference, and keeps the policy in performance mode while it "owns" the EPP updates. For non-server systems: * the default EPP for AC mode is `performance`. * the default EPP for DC mode is `balance_performance`. For server systems dynamic EPP is mostly a no-op. Signed-off-by: Mario Limonciello (AMD) --- v5->v6: * Set the power supply notifier callback before registration * Expand the changelog to cover the sysfs toggle and manual EPP blocking * Add missing kdoc --- Documentation/admin-guide/pm/amd-pstate.rst | 18 ++- drivers/cpufreq/Kconfig.x86 | 12 ++ drivers/cpufreq/amd-pstate.c | 137 ++++++++++++++++++-- drivers/cpufreq/amd-pstate.h | 10 +- 4 files changed, 163 insertions(+), 14 deletions(-) diff --git a/Documentation/admin-guide/pm/amd-pstate.rst b/Documentation/admin-guide/pm/amd-pstate.rst index d6c2f233ab239..0e4355fe13558 100644 --- a/Documentation/admin-guide/pm/amd-pstate.rst +++ b/Documentation/admin-guide/pm/amd-pstate.rst @@ -325,7 +325,7 @@ 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, if EPP feature is disabled, driver will ignore the written value +firmware, but if the dynamic EPP feature is enabled, driver will block writes. This attribute is read-write. ``boost`` @@ -347,6 +347,22 @@ boost or `1` to enable it, for the respective CPU using the sysfs path Other performance and frequency values can be read back from ``/sys/devices/system/cpu/cpuX/acpi_cppc/``, see :ref:`cppc_sysfs`. +Dynamic energy performance profile +================================== +The amd-pstate driver supports dynamically selecting the energy performance +profile based on whether the machine is running on AC or DC power. + +Whether this behavior is enabled by default with the kernel config option +`CONFIG_X86_AMD_PSTATE_DYNAMIC_EPP`. This behavior can also be overridden +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. +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. + +Attempting to manually write to the ``energy_performance_preference`` sysfs +file will fail when ``dynamic_epp`` is enabled. ``amd-pstate`` vs ``acpi-cpufreq`` ====================================== diff --git a/drivers/cpufreq/Kconfig.x86 b/drivers/cpufreq/Kconfig.x86 index 2c5c228408bf2..cdaa8d858045a 100644 --- a/drivers/cpufreq/Kconfig.x86 +++ b/drivers/cpufreq/Kconfig.x86 @@ -68,6 +68,18 @@ config X86_AMD_PSTATE_DEFAULT_MODE For details, take a look at: . +config X86_AMD_PSTATE_DYNAMIC_EPP + bool "AMD Processor P-State dynamic EPP support" + depends on X86_AMD_PSTATE + default n + help + Allow the kernel to dynamically change the energy performance + value from events like ACPI platform profile and AC adapter plug + events. + + This feature can also be changed at runtime, this configuration + option only sets the kernel default value behavior. + config X86_AMD_PSTATE_UT tristate "selftest for AMD Processor P-State driver" depends on X86 && ACPI_PROCESSOR diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c index f207252eb5f5f..2e3fb1fd280a0 100644 --- a/drivers/cpufreq/amd-pstate.c +++ b/drivers/cpufreq/amd-pstate.c @@ -36,6 +36,7 @@ #include #include #include +#include #include #include @@ -86,6 +87,11 @@ static struct cpufreq_driver amd_pstate_driver; static struct cpufreq_driver amd_pstate_epp_driver; static int cppc_state = AMD_PSTATE_UNDEFINED; static bool amd_pstate_prefcore = true; +#ifdef CONFIG_X86_AMD_PSTATE_DYNAMIC_EPP +static bool dynamic_epp = CONFIG_X86_AMD_PSTATE_DYNAMIC_EPP; +#else +static bool dynamic_epp; +#endif static struct quirk_entry *quirks; /* @@ -1155,6 +1161,74 @@ static void amd_pstate_cpu_exit(struct cpufreq_policy *policy) kfree(cpudata); } +static int amd_pstate_get_balanced_epp(struct cpufreq_policy *policy) +{ + struct amd_cpudata *cpudata = policy->driver_data; + + if (power_supply_is_system_supplied()) + return cpudata->epp_default_ac; + else + return cpudata->epp_default_dc; +} + +static int amd_pstate_power_supply_notifier(struct notifier_block *nb, + unsigned long event, void *data) +{ + struct amd_cpudata *cpudata = container_of(nb, struct amd_cpudata, power_nb); + struct cpufreq_policy *policy __free(put_cpufreq_policy) = cpufreq_cpu_get(cpudata->cpu); + u8 epp; + int ret; + + if (event != PSY_EVENT_PROP_CHANGED) + return NOTIFY_OK; + + epp = amd_pstate_get_balanced_epp(policy); + + ret = amd_pstate_set_epp(policy, epp); + if (ret) + pr_warn("Failed to set CPU %d EPP %u: %d\n", cpudata->cpu, epp, ret); + + return NOTIFY_OK; +} +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); + cpudata->dynamic_epp = false; +} + +static int amd_pstate_set_dynamic_epp(struct cpufreq_policy *policy) +{ + struct amd_cpudata *cpudata = policy->driver_data; + int ret; + u8 epp; + + policy->policy = CPUFREQ_POLICY_PERFORMANCE; + 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) { + cpudata->power_nb.notifier_call = amd_pstate_power_supply_notifier; + ret = power_supply_reg_notifier(&cpudata->power_nb); + if (ret) + goto cleanup; + } + + cpudata->dynamic_epp = true; + + return 0; + +cleanup: + amd_pstate_clear_dynamic_epp(policy); + + return ret; +} + /* Sysfs attributes */ /* @@ -1244,14 +1318,19 @@ static ssize_t store_energy_performance_preference( ssize_t ret; u8 epp; + if (cpudata->dynamic_epp) { + pr_debug("EPP cannot be set when dynamic EPP is enabled\n"); + return -EBUSY; + } + ret = sysfs_match_string(energy_perf_strings, buf); if (ret < 0) return -EINVAL; - if (!ret) - epp = cpudata->epp_default; - else + if (ret) epp = epp_values[ret]; + else + epp = amd_pstate_get_balanced_epp(policy); if (epp > 0 && policy->policy == CPUFREQ_POLICY_PERFORMANCE) { pr_debug("EPP cannot be set under performance policy\n"); @@ -1259,6 +1338,8 @@ static ssize_t store_energy_performance_preference( } ret = amd_pstate_set_epp(policy, epp); + if (ret) + return ret; return ret ? ret : count; } @@ -1620,12 +1701,40 @@ static ssize_t prefcore_show(struct device *dev, return sysfs_emit(buf, "%s\n", str_enabled_disabled(amd_pstate_prefcore)); } +static ssize_t dynamic_epp_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + return sysfs_emit(buf, "%s\n", str_enabled_disabled(dynamic_epp)); +} + +static ssize_t dynamic_epp_store(struct device *a, struct device_attribute *b, + const char *buf, size_t count) +{ + bool enabled; + int ret; + + ret = kstrtobool(buf, &enabled); + if (ret) + return ret; + + if (dynamic_epp == enabled) + return -EINVAL; + + /* reinitialize with desired dynamic EPP value */ + dynamic_epp = enabled; + ret = amd_pstate_change_driver_mode(cppc_state); + + return ret ? ret : count; +} + static DEVICE_ATTR_RW(status); static DEVICE_ATTR_RO(prefcore); +static DEVICE_ATTR_RW(dynamic_epp); static struct attribute *pstate_global_attributes[] = { &dev_attr_status.attr, &dev_attr_prefcore.attr, + &dev_attr_dynamic_epp.attr, NULL }; @@ -1715,22 +1824,20 @@ static int amd_pstate_epp_cpu_init(struct cpufreq_policy *policy) if (amd_pstate_acpi_pm_profile_server() || amd_pstate_acpi_pm_profile_undefined()) { policy->policy = CPUFREQ_POLICY_PERFORMANCE; - cpudata->epp_default = amd_pstate_get_epp(cpudata); + cpudata->epp_default_ac = cpudata->epp_default_dc = amd_pstate_get_epp(cpudata); } else { policy->policy = CPUFREQ_POLICY_POWERSAVE; - cpudata->epp_default = AMD_CPPC_EPP_BALANCE_PERFORMANCE; + cpudata->epp_default_ac = AMD_CPPC_EPP_PERFORMANCE; + cpudata->epp_default_dc = AMD_CPPC_EPP_BALANCE_PERFORMANCE; } - ret = amd_pstate_set_epp(policy, cpudata->epp_default); + if (dynamic_epp) + ret = amd_pstate_set_dynamic_epp(policy); + else + ret = amd_pstate_set_epp(policy, amd_pstate_get_balanced_epp(policy)); if (ret) goto free_cpudata1; - ret = amd_pstate_init_floor_perf(policy); - if (ret) { - dev_err(dev, "Failed to initialize Floor Perf (%d)\n", ret); - goto free_cpudata1; - } - current_pstate_driver->adjust_perf = NULL; return 0; @@ -1753,6 +1860,8 @@ static void amd_pstate_epp_cpu_exit(struct cpufreq_policy *policy) amd_pstate_update_perf(policy, perf.bios_min_perf, 0U, 0U, 0U, false); amd_pstate_set_floor_perf(policy, cpudata->bios_floor_perf); + if (cpudata->dynamic_epp) + amd_pstate_clear_dynamic_epp(policy); kfree(cpudata); policy->driver_data = NULL; } @@ -1790,6 +1899,10 @@ static int amd_pstate_epp_set_policy(struct cpufreq_policy *policy) if (!policy->cpuinfo.max_freq) return -ENODEV; + /* policy can't be changed to powersave policy while dynamic epp is enabled */ + if (policy->policy == CPUFREQ_POLICY_POWERSAVE && cpudata->dynamic_epp) + return -EBUSY; + cpudata->policy = policy->policy; ret = amd_pstate_epp_update_limit(policy, true); diff --git a/drivers/cpufreq/amd-pstate.h b/drivers/cpufreq/amd-pstate.h index 32b8b26ce388f..d929ae3163b3d 100644 --- a/drivers/cpufreq/amd-pstate.h +++ b/drivers/cpufreq/amd-pstate.h @@ -85,6 +85,11 @@ struct amd_aperf_mperf { * AMD P-State driver supports preferred core featue. * @epp_cached: Cached CPPC energy-performance preference value * @policy: Cpufreq policy value + * @suspended: If CPU core if offlined + * @epp_default_ac: Default EPP value for AC power source + * @epp_default_dc: Default EPP value for DC power source + * @dynamic_epp: Whether dynamic EPP is enabled + * @power_nb: Notifier block for power events * * The amd_cpudata is key private data for each CPU thread in AMD P-State, and * represents all the attributes and goals that AMD P-State requests at runtime. @@ -118,7 +123,10 @@ struct amd_cpudata { /* EPP feature related attributes*/ u32 policy; bool suspended; - u8 epp_default; + u8 epp_default_ac; + u8 epp_default_dc; + bool dynamic_epp; + struct notifier_block power_nb; }; /* -- 2.43.0