Re: [PATCH v2 9/9] Documentation/amd-pstate: Add documentation for amd_pstate_floor_{freq,count}

[Mario Limonciello (AMD) (kernel.org)]

On 3/11/2026 9:01 AM, Gautham R. Shenoy wrote:
> Add documentation for the sysfs files
> /sys/devices/system/cpu/cpufreq/policy*/amd_pstate_floor_freq
> and
> /sys/devices/system/cpu/cpufreq/policy*/amd_pstate_floor_count.
>
> Signed-off-by: Gautham R. Shenoy <gautham.shenoy@xxxxxxx>
Reviewed-by: Mario Limonciello (AMD) <superm1@xxxxxxxxxx>
> ---
>   Documentation/admin-guide/pm/amd-pstate.rst | 32 +++++++++++++++++++++
>   1 file changed, 32 insertions(+)
>
> diff --git a/Documentation/admin-guide/pm/amd-pstate.rst b/Documentation/admin-guide/pm/amd-pstate.rst
> index f566fea6613e6..5fd2a36f8a4b8 100644
> --- a/Documentation/admin-guide/pm/amd-pstate.rst
> +++ b/Documentation/admin-guide/pm/amd-pstate.rst
> @@ -242,6 +242,8 @@ control its functionality at the system level. They are located in the
>    /sys/devices/system/cpu/cpufreq/policy0/amd_pstate_hw_prefcore
>    /sys/devices/system/cpu/cpufreq/policy0/amd_pstate_lowest_nonlinear_freq
>    /sys/devices/system/cpu/cpufreq/policy0/amd_pstate_max_freq
> + /sys/devices/system/cpu/cpufreq/policy0/amd_pstate_floor_freq
> + /sys/devices/system/cpu/cpufreq/policy0/amd_pstate_floor_count
>    /sys/devices/system/cpu/cpufreq/policy0/amd_pstate_prefcore_ranking
>   
>   
> @@ -278,6 +280,36 @@ can change at runtime based on platform conditions. This attribute is
>   read-only.  This file is only visible on platforms which support the
>   preferred core feature.
>   
> +``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.
> +
> +
> +``amd_pstate_floor_count``
> +
> +The number of distinct Floor Performance levels supported by the
> +platform. For example, if this value is 2, then the number of unique
> +values obtained from the command ``cat
> +/sys/devices/system/cpu/cpufreq/policy*/amd_pstate_floor_freq |
> +sort -n | uniq`` should be at most this number for the behavior
> +described in ``amd_pstate_floor_freq`` to take effect. A zero value
> +implies that the platform supports unlimited floor performance levels.
> +This file is only visible on platforms that support the CPPC
> +Performance Priority feature.
> +
> +**Note**: When ``amd_pstate_floor_count`` is non-zero, the frequency to
> +which the CPU is throttled under power or thermal constraints is
> +undefined when the number of unique values of ``amd_pstate_floor_freq``
> +across all CPUs in the system exceeds ``amd_pstate_floor_count``.
> +
>   ``energy_performance_available_preferences``
>   
>   A list of all the supported EPP preferences that could be used for