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Date:   Tue, 17 Jan 2023 19:45:30 +0800
From:   Huang Rui <ray.huang@amd.com>
To:     "Yuan, Perry" <Perry.Yuan@amd.com>
Cc:     "rafael.j.wysocki@intel.com" <rafael.j.wysocki@intel.com>,
        "Limonciello, Mario" <Mario.Limonciello@amd.com>,
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        "Fontenot, Nathan" <Nathan.Fontenot@amd.com>,
        "Deucher, Alexander" <Alexander.Deucher@amd.com>,
        "Huang, Shimmer" <Shimmer.Huang@amd.com>,
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        "Meng, Li (Jassmine)" <Li.Meng@amd.com>,
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Subject: Re: [PATCH v10 02/12] Documentation: amd-pstate: add EPP profiles
 introduction
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References: <20230106061420.95715-1-perry.yuan@amd.com>
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On Fri, Jan 06, 2023 at 02:14:10PM +0800, Yuan, Perry wrote:
> From: Perry Yuan <Perry.Yuan@amd.com>
> 
> The amd-pstate driver supports a feature called energy performance
> preference (EPP). Add information to the documentation to explain
> how users can interact with the sysfs files for this feature.
> 
> 1) See all EPP profiles
> $ sudo cat /sys/devices/system/cpu/cpu0/cpufreq/energy_performance_available_preferences
> default performance balance_performance balance_power power
> 
> 2) Check current EPP profile
> $ sudo cat /sys/devices/system/cpu/cpu0/cpufreq/energy_performance_preference
> performance
> 
> 3) Set new EPP profile
> $ sudo bash -c "echo power > /sys/devices/system/cpu/cpu0/cpufreq/energy_performance_preference"
> 
> Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
> Signed-off-by: Perry Yuan <Perry.Yuan@amd.com>

Acked-by: Huang Rui <ray.huang@amd.com>

> ---
>  Documentation/admin-guide/pm/amd-pstate.rst | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
> 
> diff --git a/Documentation/admin-guide/pm/amd-pstate.rst b/Documentation/admin-guide/pm/amd-pstate.rst
> index 06e23538f79c..33ab8ec8fc2f 100644
> --- a/Documentation/admin-guide/pm/amd-pstate.rst
> +++ b/Documentation/admin-guide/pm/amd-pstate.rst
> @@ -262,6 +262,25 @@ lowest non-linear performance in `AMD CPPC Performance Capability
>  <perf_cap_>`_.)
>  This attribute is read-only.
>  
> +``energy_performance_available_preferences``
> +
> +A list of all the supported EPP preferences that could be used for
> +``energy_performance_preference`` on this system.
> +These profiles represent different hints that are provided
> +to the low-level firmware about the user's desired energy vs efficiency
> +tradeoff.  ``default`` represents the epp value is set by platform
> +firmware. This attribute is read-only.
> +
> +``energy_performance_preference``
> +
> +The current energy performance preference can be read from this attribute.
> +and user can change current preference according to energy or performance needs
> +Please get all support profiles list from
> +``energy_performance_available_preferences`` attribute, all the profiles are
> +integer values defined between 0 to 255 when EPP feature is enabled by platform
> +firmware, if EPP feature is disabled, driver will ignore the written value
> +This attribute is read-write.
> +
>  Other performance and frequency values can be read back from
>  ``/sys/devices/system/cpu/cpuX/acpi_cppc/``, see :ref:`cppc_sysfs`.
>  
> -- 
> 2.34.1
>