linux-kernel - Re: [PATCH v7 0/7] Enhanced autonomous selection and improvements

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Message-ID: <73bf9b60-7a76-4648-98cf-c37901eb7b0a@huawei.com>
Date: Sat, 31 Jan 2026 10:58:18 +0800
From: "zhenglifeng (A)" <zhenglifeng1@...wei.com>
To: Sumit Gupta <sumitg@...dia.com>, <rafael@...nel.org>,
	<viresh.kumar@...aro.org>, <pierre.gondois@....com>
CC: <ionela.voinescu@....com>, <lenb@...nel.org>, <robert.moore@...el.com>,
	<corbet@....net>, <rdunlap@...radead.org>, <ray.huang@....com>,
	<gautham.shenoy@....com>, <mario.limonciello@....com>, <perry.yuan@....com>,
	<zhanjie9@...ilicon.com>, <linux-pm@...r.kernel.org>,
	<linux-acpi@...r.kernel.org>, <linux-doc@...r.kernel.org>,
	<acpica-devel@...ts.linux.dev>, <linux-kernel@...r.kernel.org>,
	<linux-tegra@...r.kernel.org>, <treding@...dia.com>, <jonathanh@...dia.com>,
	<vsethi@...dia.com>, <ksitaraman@...dia.com>, <sanjayc@...dia.com>,
	<nhartman@...dia.com>, <bbasu@...dia.com>
Subject: Re: [PATCH v7 0/7] Enhanced autonomous selection and improvements

Reviewed-by: Lifeng Zheng <zhenglifeng1@...wei.com>

On 2026/1/29 18:48, Sumit Gupta wrote:
> As discussed in [7], v5 was split into two parts. This is part 1.
> - Patch 1-3 from v6: Applied by Rafael for 6.20.
> - Remaining patches: Included in this v7 with review comments addressed.
> Part 2 (v5 patches 8-11) will follow separately.
> 
> This patch series adds sysfs interfaces for CPPC min_perf, max_perf,
> and perf_limited registers, along with supporting ACPI APIs and
> improvements for the cppc_cpufreq driver.
> 
> CPPC autonomous mode (auto_sel) enables hardware-driven CPU performance
> scaling using Energy Performance Preference (EPP) hints. Currently,
> there's limited runtime control and visibility into CPPC performance
> registers.
> 
> This series addresses these gaps by:
> 1. Exposing min_perf/max_perf registers via sysfs (as frequency in kHz)
>    to allow fine-grained performance bounds control in autonomous mode.
> 2. Exposing perf_limited register to detect and clear throttling events.
> 
> It also includes code improvements: new APIs for reading performance
> controls, a warning for missing mandatory DESIRED_PERF register, and
> extended epp_perf support.
> 
> The patches are grouped as below:
> - Patch 1: Add cppc_get_perf() API (independent).
> - Patch 2: Warn on missing mandatory DESIRED_PERF (independent).
> - Patch 3: Extend cppc_set_epp_perf for FFH/SystemMemory (independent)
> - Patch 4-5: APIs, sysfs for min/max_perf, perf_limited (independent)
> - Patch 6: Doc for min/max_perf and perf_limited (depends on 4-5)
> - Patch 7: Update cached perf_ctrls on sysfs write (independent).
> 
> ---
> v6[7] -> v7:
> - patch 1-3 (v6): Dropped as they were applied by Rafael for 6.20.
> - patch 2 (v7): Added new patch to warn on missing DESIRED_PERF as
>   suggested by Pierre.
> - patch 4, 7 (v7): Removed mutex from sysfs store functions as
>   policy->rwsem already provides synchronization.
> - patch 4 (v7): Added validation checks in store_min/max_perf.
> 
> Sumit Gupta (7):
>   ACPI: CPPC: Add cppc_get_perf() API to read performance controls
>   ACPI: CPPC: Warn on missing mandatory DESIRED_PERF register
>   ACPI: CPPC: Extend cppc_set_epp_perf() for FFH/SystemMemory
>   ACPI: CPPC: add APIs and sysfs interface for min/max_perf
>   ACPI: CPPC: add APIs and sysfs interface for perf_limited
>   cpufreq: CPPC: Add sysfs for min/max_perf and perf_limited
>   cpufreq: CPPC: Update cached perf_ctrls on sysfs write
> 
>  .../ABI/testing/sysfs-devices-system-cpu      |  44 ++++
>  drivers/acpi/cppc_acpi.c                      | 214 +++++++++++++++++-
>  drivers/cpufreq/cppc_cpufreq.c                | 207 ++++++++++++++++-
>  include/acpi/cppc_acpi.h                      |  40 ++++
>  4 files changed, 500 insertions(+), 5 deletions(-)
> 
> [1] https://lore.kernel.org/lkml/20250211103737.447704-1-sumitg@nvidia.com/
> [2] https://lore.kernel.org/lkml/20250823200121.1320197-1-sumitg@nvidia.com/
> [3] https://lore.kernel.org/lkml/20251001150104.1275188-1-sumitg@nvidia.com/
> [4] https://lore.kernel.org/lkml/20251105113844.4086250-1-sumitg@nvidia.com/
> [5] https://lore.kernel.org/lkml/20251223121307.711773-1-sumitg@nvidia.com/
> [6] https://lore.kernel.org/lkml/20260120145623.2959636-1-sumitg@nvidia.com/
> [7] https://lore.kernel.org/lkml/66f58f43-631b-40a0-8d42-4e90cd24b757@arm.com/
>