[PATCH 0/6] Add CPPC HighestFreq support

Mario Limonciello (AMD)
2026-04-27T03:55:29Z

On some systems, the boost ratio cannot be accurately calculated
using linear interpolation of CPPC performance values because the
performance-to-frequency mapping is not linear across all cores.

This series introduces support for the CPPC HighestFreq register. This
register is under a proposal with ASWG at the moment and trending for
inclusion in ACPI 6.7.

This optionally provides the actual highest frequency eliminating
the need for interpolation. When available, this frequency value is used
for more accurate CPU capacity calculations and boost ratio determination.

This series brings the existing CPPC definitions up to ACPI 6.6 and then
adds support for the ACPI 6.7 proposal.

Mario Limonciello (6):
Revert "ACPI: CPPC: Adjust debug messages in amd_set_max_freq_ratio()
to warn"
ACPI: Add CPPC v4 definitions
ACPI: CPPC: Add support for reading HighestFreq
ACPI: CPPC: Refactor boost ratio handling
cpufreq/acpi-cpufreq: Use amd_get_boost_ratio()
cpufreq/amd-pstate: Get highest freq from CPPC if available

arch/x86/kernel/acpi/cppc.c | 122 ++++++++++++++++++---------------
drivers/acpi/cppc_acpi.c | 39 ++++++++---
drivers/cpufreq/acpi-cpufreq.c | 17 +++--
drivers/cpufreq/amd-pstate.c | 18 +++--
include/acpi/cppc_acpi.h | 27 ++++++--
5 files changed, 139 insertions(+), 84 deletions(-)

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2.43.0