[PATCH 0/2] ACPI: CPPC: Add CPPC v4 support (ACPI 6.6)

Sumit Gupta
2026-04-27T05:18:49Z

Add initial kernel support for CPPC v4 (ACPI 6.6, Section 8.4.6),
which extends the _CPC package from 23 to 25 entries with two
optional fields:

- OSPM Nominal Performance (8.4.6.1.2.6): write-only register
used by OSPM to tell the platform what it considers nominal.
The platform classifies performance above this as boost and
below as throttle for power/thermal decisions.

- Resource Priority (8.4.6.1.2.7): Package of Resource Priority
Register Descriptor sub-packages. Full parsing is not yet
implemented; such entries are marked as unsupported.

Patch 1: Add v4 _CPC parsing - validate the 25-entry layout,
handle the Resource Priority package, and mark the two new
registers optional.

Patch 2: cppc_set_ospm_nominal_perf() API, write-only
acpi_cppc/ospm_nominal_perf sysfs attribute, and init to platform
nominal during cppc_cpufreq policy init.

Sumit Gupta (2):
ACPI: CPPC: Add support for CPPC v4
ACPI: CPPC: Add ospm_nominal_perf support

drivers/acpi/cppc_acpi.c | 66 ++++++++++++++++++++++++++++++----
drivers/cpufreq/cppc_cpufreq.c | 10 ++++++
include/acpi/cppc_acpi.h | 13 +++++--
3 files changed, 81 insertions(+), 8 deletions(-)

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2.34.1