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

[Artem Bityutskiy]

On Tue, 2026-02-03 at 13:43 +0100, Rafael J. Wysocki wrote:
> On Thu, Jan 29, 2026 at 11:49 AM Sumit Gupta <sumitg@xxxxxxxxxx> wrote:
> > 
> > Add cppc_get/set_min_perf() and cppc_get/set_max_perf() APIs to read and
> > write the MIN_PERF and MAX_PERF registers.
> > 
> > Also add sysfs interfaces (min_perf, max_perf) in cppc_cpufreq driver
> > to expose these controls to userspace. The sysfs values are in frequency
> > (kHz) for consistency with other cpufreq sysfs files.
> 
> But this is not cpufreq and it is not consistent.

Just my 2 cents to add:

CPPC and Intel CPUs don't use kHz for performance scaling. We should
avoid introducing additional kHz-based interfaces where possible, since
the performance units <-> kHz translation may become more complex over
time than today. Future implementations could involve non-linear
relationships and reduced accuracy. Minimizing kHz interfaces now may
help reduce future work.

Thanks,
Artem.