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Thu, 16 Jul 2026 08:38:24 -0700 From: Sumit Gupta To: , , , , , , , , , , , , CC: , , , , , , , Subject: [PATCH v2 0/3] cpufreq: CPPC: Preserve OSPM-set registers across hotplug and unload Date: Thu, 16 Jul 2026 21:08:17 +0530 Message-ID: <20260716153820.2007095-1-sumitg@nvidia.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-NVConfidentiality: public Content-Transfer-Encoding: 8bit Content-Type: text/plain X-NV-OnPremToCloud: ExternallySecured X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BL6PEPF0001AB57:EE_|PH0PR12MB7929:EE_ X-MS-Office365-Filtering-Correlation-Id: a3102bb9-d1b7-4e1b-69b2-08dee3505b78 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|23010399003|7416014|376014|36860700016|82310400026|1800799024|13003099007|921020|10067099003|56012099006|11063799006|18002099003; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:216.228.117.161;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:dc6edge2.nvidia.com;CAT:NONE;SFS:(13230040)(23010399003)(7416014)(376014)(36860700016)(82310400026)(1800799024)(13003099007)(921020)(10067099003)(56012099006)(11063799006)(18002099003);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: mJ3uox+V/S0Cwn+SrmuO2koBgpRDMsO+mWvqgQSmScbsZY/+T0uDpEM+dDBooN84rZosnNqxopyg5zBqE4/hqs2vnYJAh48S85IsxoBw8CYIHSIAJqg/HkOjhegLc2+lLxBSGBwdI63zE5bojtYmCpQGNykBJdQIntKkmI9IrAdmEWp7lwDP/s8YJVi2sVVZ5zDcClXoa0qUuKpIl0SqopnYR0lh3BY2b+4Zvii6OsmsG+7tVZSaQ5aLU5S0jZJOn+QAHWz6vgwsRrrqw5N9ate0LNUc1eYozCztnjREJ8ciFgRPRHjZt67pDUts7g0tsnx2wMzhogSzvxzKXBLFyTz2cT/756S0v5sfwvUouT+1d3JWHNfqKZ+p8lKt65TtjdL2wY/yKZ0wvNQ/eVMcPHsYjMPF8Mccn4qRogaHTZ0C+i8e0BXtFcOC+dB/jCyn X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 16 Jul 2026 15:39:00.2330 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: a3102bb9-d1b7-4e1b-69b2-08dee3505b78 X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.117.161];Helo=[mail.nvidia.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: PH0PR12MB7929 CPPC registers that OSPM programs at runtime, via sysfs (auto_sel, energy_performance_preference, auto_act_window) or via the autonomous mode boot parameter, can be silently lost across CPU hotplug or left behind on driver unload: - Across CPU hotplug: the cpufreq core tears the policy down and the platform may reset the registers while the CPU is offline. - On driver unload: the value the driver wrote is left in the register instead of returning to its pre-driver state. This series makes cppc_cpufreq keep these values consistent: - Patch 1: adds online()/offline() callbacks so core keeps the policy alive across CPU hotplug instead of tearing it down and rebuilding it. - Patch 2: adds u64 wrappers for the autonomous selection register. - Patch 3: adds a table-driven mechanism that captures each register's firmware value, restores it when the policy goes down, and reapplies the OSPM-set value when the policy comes back online. v[1] -> v2: - New patch 1: keep policy across hotplug by adding online()/offline(). - New patch 2: move the auto_sel u64 wrappers into cppc_acpi.c. - Restore fw values from offline(), which covers both hotplug and unload - Drop cppc_cache_perf_ctrls() and read reg values at offline() instead of caching them. - Add auto_act_window and defer OSPM Nominal Perf to a later series. Sumit Gupta (3): cpufreq: CPPC: Keep the policy across CPU hotplug ACPI: CPPC: Add u64 wrappers for the autonomous selection register cpufreq: CPPC: Preserve OSPM-set registers across hotplug and unload drivers/acpi/cppc_acpi.c | 40 +++++++++ drivers/cpufreq/cppc_cpufreq.c | 156 +++++++++++++++++++++++++++++++++ include/acpi/cppc_acpi.h | 10 +++ 3 files changed, 206 insertions(+) [1] v1: https://lore.kernel.org/lkml/20260623095403.3407436-1-sumitg@nvidia.com/ -- 2.34.1