Re: [PATCH v8 0/7] Enhanced autonomous selection and improvements

From: Sumit Gupta

Date: Tue Mar 03 2026 - 12:33:10 EST



On 28/02/26 02:06, Rafael J. Wysocki wrote:
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On Thu, Feb 26, 2026 at 2:59 PM Sumit Gupta <sumitg@xxxxxxxxxx> wrote:

This patch series improves the CPPC cpufreq driver with new ACPI APIs
and enhancements for Autonomous Selection (auto_select).

CPPC auto_select enables hardware-driven CPU performance scaling using
Energy Performance Preference (EPP) hints. Currently, there's limited
runtime control and visibility into CPPC performance registers.

The series adds cppc_get_perf() API to read performance controls, updates
MIN_PERF/MAX_PERF in target callbacks using existing scaling_min/max_freq
interface similar to intel_cpufreq HWP handling, and exposes perf_limited
register via sysfs to detect throttling events.

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: Update cached perf_ctrls on sysfs write (independent).
- Patch 5: Update MIN_PERF/MAX_PERF in target callbacks (depends on 4).
- Patch 6-7: APIs, sysfs and doc for perf_limited (independent).
Gentle ping.

If there are no further comments, could this be considered for merging.
Applied as 7.1 material, thanks!

Thank you for applying the series.


That said, wouldn't it be prudent to check cpc_read() return values everywhere? They are handled quite inconsistently and this series doesn't improve that.

I will send a follow-up patch to address this.

Thank you
Sumit Gupta