[PATCH v7 0/7] Enhanced autonomous selection and improvements

[Sumit Gupta <sumitg@nvidia.com>]

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/

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2.34.1