Re: [PATCH v7 4/7] ACPI: CPPC: add APIs and sysfs interface for min/max_perf

[Russell Haley <yumpusamongus@gmail.com>]

On 1/31/26 7:58 AM, Sumit Gupta wrote:
> 
> On 31/01/26 09:36, zhenglifeng (A) wrote:
>> External email: Use caution opening links or attachments
>>
>>
>> Hi Sumit,
>>
>> I am thinking that maybe it is better to call these two sysfs interface
>> 'min_freq' and 'max_freq' as users read and write khz instead of raw
>> value.
> 
> Thanks for the suggestion.
> Kept min_perf/max_perf to match the CPPC register names
> (MIN_PERF/MAX_PERF), making it clear to users familiar with
> CPPC what's being controlled.
> The kHz unit is documented in the ABI.
> 
> Thank you,
> Sumit Gupta

On my x86 machine with kernel 6.18.5, the kernel is exposing raw values:

> grep . /sys/devices/system/cpu/cpu0/acpi_cppc/*
/sys/devices/system/cpu/cpu0/acpi_cppc/feedback_ctrs:ref:342904018856568
del:437439724183386
/sys/devices/system/cpu/cpu0/acpi_cppc/guaranteed_perf:63
/sys/devices/system/cpu/cpu0/acpi_cppc/highest_perf:88
/sys/devices/system/cpu/cpu0/acpi_cppc/lowest_freq:0
/sys/devices/system/cpu/cpu0/acpi_cppc/lowest_nonlinear_perf:36
/sys/devices/system/cpu/cpu0/acpi_cppc/lowest_perf:1
/sys/devices/system/cpu/cpu0/acpi_cppc/nominal_freq:3900
/sys/devices/system/cpu/cpu0/acpi_cppc/nominal_perf:62
/sys/devices/system/cpu/cpu0/acpi_cppc/reference_perf:62
/sys/devices/system/cpu/cpu0/acpi_cppc/wraparound_time:18446744073709551615

It would be surprising for a nearby sysfs interface with very similar
names to use kHz instead.

Thanks,

Russell Haley