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Shenoy" To: Mario Limonciello , "Rafael J . Wysocki" , Viresh Kumar , K Prateek Nayak CC: , , "Gautham R. Shenoy" , Jonathan Corbet , "Shuah Khan" Subject: [PATCH 9/9] Documentation/amd-pstate: Add documentation for amd_pstate_floor_{freq,count} Date: Fri, 6 Mar 2026 15:27:53 +0530 Message-ID: <20260306095753.17155-10-gautham.shenoy@amd.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260306095753.17155-1-gautham.shenoy@amd.com> References: <20260306095753.17155-1-gautham.shenoy@amd.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: satlexmb08.amd.com (10.181.42.217) To satlexmb07.amd.com (10.181.42.216) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BN2PEPF000044A1:EE_|IA0PR12MB7674:EE_ X-MS-Office365-Filtering-Correlation-Id: c0484825-48cb-4c1d-c713-08de7b66f276 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|82310400026|376014|1800799024|36860700016; 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)(82310400026)(376014)(1800799024)(36860700016);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: mW71fTaeiUPerimY26TPzWuqSboZrjLHX0Fn+Cy01b50aROPdIcGtY8tBtpdmVhuRBXZzp61y/XH5+J7CYgbuxWN65QFEpgmtGLRJWpHWaDougQz7c6lG/9As0z71xvozftzowxx+w9KP8kGWcahL2BJh8/Y3kfuH6tRtzwnZjMXNByzril5gOABbVORecNA+XA6rpzoOyF+oN+iWwKUxJILTKW8LeQtBRDMGqIhCKDlC/TdWR6KugI6CvhPzj588CDxVAtD/Tz6S2FJ0bdwFUnV1uyqzkLl7fKxy567EdRzYcBhLujQdX3DhTvFbWomItyACwPE8p6eee7X9BNjHDplM8tcrFwh05mdw+8EIOcdZy+z72Fv8Ni0fxtY2h7n1X4CzSqZSr98aar6hTzvUi1CSSBxrE4TwIZRjQUs4t5eA7Ed56Xg4RABGo88nbSt X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 06 Mar 2026 09:58:41.7551 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: c0484825-48cb-4c1d-c713-08de7b66f276 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: BN2PEPF000044A1.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: IA0PR12MB7674 Content-Type: text/plain; charset="utf-8" Add documentation for the sysfs files /sys/devices/system/cpu/cpufreq/policy*/amd_pstate_floor_freq and /sys/devices/system/cpu/cpufreq/policy*/amd_pstate_floor_count. Signed-off-by: Gautham R. Shenoy --- Documentation/admin-guide/pm/amd-pstate.rst | 32 +++++++++++++++++++++ 1 file changed, 32 insertions(+) diff --git a/Documentation/admin-guide/pm/amd-pstate.rst b/Documentation/ad= min-guide/pm/amd-pstate.rst index f566fea6613e6..5fd2a36f8a4b8 100644 --- a/Documentation/admin-guide/pm/amd-pstate.rst +++ b/Documentation/admin-guide/pm/amd-pstate.rst @@ -242,6 +242,8 @@ control its functionality at the system level. They are= located in the /sys/devices/system/cpu/cpufreq/policy0/amd_pstate_hw_prefcore /sys/devices/system/cpu/cpufreq/policy0/amd_pstate_lowest_nonlinear_freq /sys/devices/system/cpu/cpufreq/policy0/amd_pstate_max_freq + /sys/devices/system/cpu/cpufreq/policy0/amd_pstate_floor_freq + /sys/devices/system/cpu/cpufreq/policy0/amd_pstate_floor_count /sys/devices/system/cpu/cpufreq/policy0/amd_pstate_prefcore_ranking =20 =20 @@ -278,6 +280,36 @@ can change at runtime based on platform conditions. Th= is attribute is read-only. This file is only visible on platforms which support the preferred core feature. =20 +``amd_pstate_floor_freq`` + +The floor frequency associated with each CPU. Userspace can write any +value between ``cpuinfo_min_freq`` and ``scaling_max_freq`` into this +file. When the system is under power or thermal constraints, the +platform firmware will attempt to throttle the CPU frequency to the +value specified in ``amd_pstate_floor_freq`` before throttling it +further. This allows userspace to specify different floor frequencies +to different CPUs. For optimal results, threads of the same core +should have the same floor frequency value. This file is only visible +on platforms that support the CPPC Performance Priority feature. + + +``amd_pstate_floor_count`` + +The number of distinct Floor Performance levels supported by the +platform. For example, if this value is 2, then the number of unique +values obtained from the command ``cat +/sys/devices/system/cpu/cpufreq/policy*/amd_pstate_floor_freq | +sort -n | uniq`` should be at most this number for the behavior +described in ``amd_pstate_floor_freq`` to take effect. A zero value +implies that the platform supports unlimited floor performance levels. +This file is only visible on platforms that support the CPPC +Performance Priority feature. + +**Note**: When ``amd_pstate_floor_count`` is non-zero, the frequency to +which the CPU is throttled under power or thermal constraints is +undefined when the number of unique values of ``amd_pstate_floor_freq`` +across all CPUs in the system exceeds ``amd_pstate_floor_count``. + ``energy_performance_available_preferences`` =20 A list of all the supported EPP preferences that could be used for --=20 2.34.1