From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from MW6PR02CU001.outbound.protection.outlook.com (mail-westus2azon11012037.outbound.protection.outlook.com [52.101.48.37]) (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 C61C631352A; Tue, 30 Jun 2026 19:03:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=52.101.48.37 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782846210; cv=fail; b=UHn3BTuGzavF27rvXWC66Qj58QOG7AIRrB0ttIyEE5rlKStR+AltHFojOXo6o8H3MQSIUclJ5n7aUTsuf2OHCpgotyb7UbC/sAU2p72Vc4xHDnoPtSnhA4tsq0rBGAi/3DdXuA95s7yVRW3LJlQTIp1WCPI96EDtbGc0Ndk3GwQ= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782846210; c=relaxed/simple; bh=2JGdMvrNAVI4eJ+LCBexfUHd5bUiG2HA2TgtBNyTGgY=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=hzJKLraJftqMVCPEU0UIPSGEgLjAjXaTYjznsVX01e/b3ML1h8doa8aJ0tGn41hnAJpQ5uuG1QxYqqLE1FeglnD4ZwbugFKZyfFWJii3jkbA4nryW0qzYQJFsViKniRhZT+c3GHTqpq5au4YQWUrEWBXc/JV/cE1DbgCOPttuJ4= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amd.com; spf=fail smtp.mailfrom=amd.com; dkim=pass (1024-bit key) header.d=amd.com header.i=@amd.com header.b=iGRYMG0U; arc=fail smtp.client-ip=52.101.48.37 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amd.com Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=amd.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=amd.com header.i=@amd.com header.b="iGRYMG0U" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=qFTFM12sEnTydwrtcz/3tbhOjNcs5DMN0GEj3UAdq2z6OzQFJz5UsgeDsyUnGzUm2gQUmk7XWClG4Og1Nidq5MXIjnJvEC2RCWEr+916v1YUYk4wJHbDXmrGK4fdPDWErmMLOwOSoGx274XznQutaEVDylhSJHyDt8NyHcWjGjI3cC1D53p1AJsovbq3tnjZjkMnKQ/SM/Cl+4TciT14VsEVaLpdnJjuerVHGBSCWmGzOUbOSHxfQ0vbottX7RHUUS4fMnyYJGzEOYAT9u7pCRubhqiDEc3gdzFvoUSDFSWrgFfKuHVJD1ZGRhRn00FsyhLrINgihw71G8Sxo5TcpA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=jcOx4/0H8XjpaRI2A1rf6LaKUjmrySUPDevqH+Wm/F0=; b=U8Gvz07ogDFpLLZhl1gn1ohuOo7m3cf5XQrQrpOSUiDVSEzYIw5e7Se8G2XHGcXZZP3sqJ+PcZTRAHAf7F4ZCQPbm+5yMoAZxSuXyExLL6Cj80JFnzYCdJWqGg9zM+ZOBBrMSJLfyMKEPdT2EQu3dVSNyxo70M86roAT67qaHh8YHbPcoG2/rYbhQETY0Mhj56+yDeJTVWdgO62EH6CB6XXWlYWDZ1EKhO/rp+sXAqqZN5L5mNVsoyAAkY2UTXj0AG7gB/RNbUiciVV3C2Je8UViaLB8ZeMAmC/a3xT/Ksp8e4VhpHysMhHnsJXDP7CNDcAtdiXgc/AuZYiy21v++Q== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass (sender ip is 165.204.84.17) smtp.rcpttodomain=kernel.org smtp.mailfrom=amd.com; dmarc=pass (p=quarantine sp=quarantine pct=100) action=none header.from=amd.com; dkim=none (message not signed); arc=none (0) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amd.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=jcOx4/0H8XjpaRI2A1rf6LaKUjmrySUPDevqH+Wm/F0=; b=iGRYMG0UnejZlrL7PYCoEWEL7Vod8+qcoPYhXgDtJCy//0HIY+Ztl2MZNNt0wm917vCS4T6UJJLEzlb9dnwdAcIpy3nTShW2ECWF1sPvYKwuW3hMzn3vpknMNNAsyHn1uohHstoIHDjd02CsTYpoGpLVGmpsiY8dQpeeO8LldZ8= Received: from BLAPR03CA0027.namprd03.prod.outlook.com (2603:10b6:208:32b::32) by IA1PR12MB6553.namprd12.prod.outlook.com (2603:10b6:208:3a3::8) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.159.14; Tue, 30 Jun 2026 19:03:18 +0000 Received: from BL6PEPF0001AB57.namprd02.prod.outlook.com (2603:10b6:208:32b:cafe::9a) by BLAPR03CA0027.outlook.office365.com (2603:10b6:208:32b::32) with Microsoft SMTP Server (version=TLS1_3, cipher=TLS_AES_256_GCM_SHA384) id 15.21.181.8 via Frontend Transport; Tue, 30 Jun 2026 19:03:18 +0000 X-MS-Exchange-Authentication-Results: spf=pass (sender IP is 165.204.84.17) smtp.mailfrom=amd.com; dkim=none (message not signed) header.d=none;dmarc=pass action=none header.from=amd.com; Received-SPF: Pass (protection.outlook.com: domain of amd.com designates 165.204.84.17 as permitted sender) receiver=protection.outlook.com; client-ip=165.204.84.17; helo=satlexmb07.amd.com; pr=C Received: from satlexmb07.amd.com (165.204.84.17) by BL6PEPF0001AB57.mail.protection.outlook.com (10.167.241.9) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.181.6 via Frontend Transport; Tue, 30 Jun 2026 19:03:18 +0000 Received: from BLRKPRNAYAK.amd.com (10.180.168.240) by satlexmb07.amd.com (10.181.42.216) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.2562.41; Tue, 30 Jun 2026 14:00:54 -0500 From: K Prateek Nayak To: Mario Limonciello , "Rafael J. Wysocki" , Viresh Kumar , Huang Rui , Jonathan Corbet , Shuah Khan CC: Perry Yuan , K Prateek Nayak , , , Subject: [RFC PATCH 4/6] Documentation/amd-pstate: Update dynamic_epp documentation with new behavior Date: Tue, 30 Jun 2026 18:59:02 +0000 Message-ID: <20260630185904.5602-5-kprateek.nayak@amd.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260630185904.5602-1-kprateek.nayak@amd.com> References: <20260630185904.5602-1-kprateek.nayak@amd.com> Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-ClientProxiedBy: satlexmb07.amd.com (10.181.42.216) To satlexmb07.amd.com (10.181.42.216) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BL6PEPF0001AB57:EE_|IA1PR12MB6553:EE_ X-MS-Office365-Filtering-Correlation-Id: 47478640-8551-4073-b4da-08ded6da3f19 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|82310400026|36860700016|1800799024|23010399003|18002099003|11063799006|22082099003|6133799003|56012099006|3023799007; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:satlexmb07.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230040)(376014)(82310400026)(36860700016)(1800799024)(23010399003)(18002099003)(11063799006)(22082099003)(6133799003)(56012099006)(3023799007);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: JfKo+uWRFokkGycKtr6xJRX7CNHBRji/jwQ6oRmh0dU7agcDjqUASXoMWsVmblClEdYBAmgjlyd28qRsR9080i5MuAIepuZmZKN7dupEvRFs3Q9Y9QyZULbzgHJjEJ4jNDWfCJyjGwH5vEYiGBmvzt+fI9Izi2+B4dKLWA25o6IZbmaQ8t+o+71MkS7nnIb9EVglrOzfSvCYjpf3GyePPYd8lGPhcaZPi7uOWgp6437k2F6UQZDXY9vhuFubdvGT7U7s8QvDVwniwtwyyK/f2WSzdUfG1P2+667jvN0rvQOAy29bTC1SWPzMiSbpQWaEV2wGsT5r5eCZECTBUNGydnRrAsgdsSaiYzc5f/6sHD9qgsBtqi31VrnoZr6mwVHFX4FP4NK37W7d+lsIaNGvq3maT1G+n/7CSMRNm6Pzlv/6yJwnGyOqGFVWxrQQZyBR X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 30 Jun 2026 19:03:18.1927 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 47478640-8551-4073-b4da-08ded6da3f19 X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[satlexmb07.amd.com] X-MS-Exchange-CrossTenant-AuthSource: BL6PEPF0001AB57.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: IA1PR12MB6553 Update the admin-guide for dynamic_epp describing the latest integration into energy_performance_preference selections. Signed-off-by: K Prateek Nayak --- Documentation/admin-guide/pm/amd-pstate.rst | 61 +++++++++++++-------- 1 file changed, 38 insertions(+), 23 deletions(-) diff --git a/Documentation/admin-guide/pm/amd-pstate.rst b/Documentation/admin-guide/pm/amd-pstate.rst index a95e2ebce005..1afc2f8b3f0e 100644 --- a/Documentation/admin-guide/pm/amd-pstate.rst +++ b/Documentation/admin-guide/pm/amd-pstate.rst @@ -317,7 +317,10 @@ 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. ``custom`` designates that integer values 0-255 may be written -as well. This attribute is read-only. +as well. ``dynamic`` designates that the EPP is modified dynamically +by the platform profile and the power supply status. See ``Dynamic energy +performance profile`` section below to know more about the ``dynamic`` +mode. This attribute is read-only. ``energy_performance_preference`` @@ -326,13 +329,11 @@ and user can change current preference according to energy or performance needs Coarse named profiles are available in the attribute ``energy_performance_available_preferences``. Users can also write individual integer values between 0 to 255. -When dynamic EPP is enabled, writes to energy_performance_preference are blocked -even when EPP feature is enabled by platform firmware. 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. +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`` The `boost` sysfs attribute provides control over the CPU core @@ -356,21 +357,35 @@ Other performance and frequency values can be read back from 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 depends on the kernel command line option -``amd_dynamic_epp`` is set. This behavior can also be overridden -at runtime by the sysfs file ``/sys/devices/system/cpu/amd_pstate/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. 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. - -Attempting to manually write to the ``energy_performance_preference`` sysfs -file will fail when ``dynamic_epp`` is enabled. +profile based on whether the machine is running on AC or DC power in active +mode. + +The ``dynamic`` mode is listed in +``/sys/devices/system/cpu/cpuX/cpufreq/energy_performance_available_preferences`` +when available while running under the ``powersave`` governor. The ``dynamic`` +mode can be toggled on by writing the same to the sysfs file +``/sys/devices/system/cpu/cpuX/cpufreq/energy_performance_preference`` when +available. + +When ``amd_dynamic_epp=disable`` is added to the kernel command line, +``dynamic`` option is not available in +``energy_performance_available_preferences`` and the feature cannot be toggled +at runtime. + +When ``amd_dynamic_epp=enable`` is added to the kernel command line, ``dynamic`` +option is selected by default as ``energy_performance_preference`` when +amd-pstate-epp driver is loaded. + +The availability of ``dynamic`` option as an ``energy_performance_preference`` +can be found by inspecting the sysfs files +``/sys/devices/system/cpu/amd_pstate/dynamic_epp`` and +``/sys/devices/system/cpu/cpuX/cpufreq/energy_performance_available_preferences`` + +When ``energy_performance_preference`` is set to ``dynamic``, the driver will +select a different energy performance 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. ``amd-pstate`` vs ``acpi-cpufreq`` ====================================== -- 2.34.1