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

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Message-ID: <6652394f-7a44-44e9-8220-4dd45624729c@arm.com>
Date: Fri, 30 Jan 2026 09:23:46 +0100
From: Pierre Gondois <pierre.gondois@....com>
To: Sumit Gupta <sumitg@...dia.com>, rafael@...nel.org,
 viresh.kumar@...aro.org, zhenglifeng1@...wei.com, 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
Cc: 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

Hi Sumit,

For the whole patch-set:

Reviewed-by: Pierre Gondois <pierre.gondois@....com>

Thanks

On 1/29/26 11:48, 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/
>