Re: [PATCH 9/9] Documentation/amd-pstate: Add documentation for amd_pstate_floor_{freq,count}

[Gautham R. Shenoy]

Hello Prateek,

On Tue, Mar 10, 2026 at 09:15:03AM +0530, K Prateek Nayak wrote:
> Hello Gautham,
> 
> On 3/6/2026 3:27 PM, Gautham R. Shenoy wrote:
> > +``amd_pstate_floor_freq``
> > +
> > +The floor frequency associated with each CPU. Userspace can write any
> > +value between ``cpuinfo_min_freq`` and ``scaling_max_freq`` into this
> > +file. When the system is under power or thermal constraints, the
> > +platform firmware will attempt to throttle the CPU frequency to the
> > +value specified in ``amd_pstate_floor_freq`` before throttling it
> > +further. This allows userspace to specify different floor frequencies
> > +to different CPUs. For optimal results, threads of the same core
> > +should have the same floor frequency value. This file is only visible
> > +on platforms that support the CPPC Performance Priority feature.
> 
> nit. Should we note that the driver caches the closes perf value and the
> read of the file will output the corresponding frequency of the perf
> level?
> 
> Otherwise, it might come as a surprise to the user that the read of file
> returns a value very close to what was written but not exactly equal to
> it all the times.
> 
> Or should we just cache the raw frequency value when user modifies it
> and keep the perf translation bits opaque to the user?

I think it is better to cache the user requested value of
amd_pstate_floor_freq in cpudata and report the same when the user
reads the sysfs file.

I will change this in v2. Thanks for the feedback.

> 
> -- 
> Thanks and Regards,
> Prateek
> 

-- 
Thanks and Regards
gautham.