Re: [PATCH v5 2/5] cpufreq/amd-pstate: add kernel command line to override dynamic epp

["Gautham R. Shenoy" <gautham.shenoy@amd.com>]

On Mon, Jan 05, 2026 at 11:14:38PM -0600, Mario Limonciello wrote:
> From: Mario Limonciello <mario.limonciello@amd.com>
> 
> Add `amd_dynamic_epp=enable` and `amd_dynamic_epp=disable` to override
> the kernel configuration option `CONFIG_X86_AMD_PSTATE_DYNAMIC_EPP`
> locally.
> 
> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
> ---
>  Documentation/admin-guide/kernel-parameters.txt |  7 +++++++
>  Documentation/admin-guide/pm/amd-pstate.rst     |  7 +++++++
>  drivers/cpufreq/amd-pstate.c                    | 11 +++++++++++
>  3 files changed, 25 insertions(+)
> 
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index a8d0afde7f85a..d7d547bbda430 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -490,6 +490,13 @@ Kernel parameters
>  			disable
>  			  Disable amd-pstate preferred core.
>  
> +	amd_dynamic_epp=
> +			[X86]
> +			disable
> +			  Disable amd-pstate dynamic EPP.
> +			enable
> +			  Enable amd-pstate dynamic EPP.
> +
>  	amijoy.map=	[HW,JOY] Amiga joystick support
>  			Map of devices attached to JOY0DAT and JOY1DAT
>  			Format: <a>,<b>
> diff --git a/Documentation/admin-guide/pm/amd-pstate.rst b/Documentation/admin-guide/pm/amd-pstate.rst
> index 5aa9fb77a078c..df4607b6a5f62 100644
> --- a/Documentation/admin-guide/pm/amd-pstate.rst
> +++ b/Documentation/admin-guide/pm/amd-pstate.rst
> @@ -438,6 +438,13 @@ For systems that support ``amd-pstate`` preferred core, the core rankings will
>  always be advertised by the platform. But OS can choose to ignore that via the
>  kernel parameter ``amd_prefcore=disable``.
>  
> +``amd_dynamic_epp``
> +
> +When AMD pstate is in auto mode, dynamic EPP will control whether the kernel
> +autonomously changes the EPP mode. The default is configured by
> +``CONFIG_X86_AMD_PSTATE_DYNAMIC_EPP`` but can be explicitly enabled with
> +``amd_pstate_epp=enable`` or disabled with ``amd_pstate_epp=disable``.

Do you mean amd_dynamic_epp instead of amd_pstate_epp here ?

The code and kernel-parameters.txt both use
amd_dynamic_epp, not amd_pstate_epp:

drivers/cpufreq/amd-pstate.c:
    early_param("amd_dynamic_epp", amd_dynamic_epp_param);

Documentation/admin-guide/kernel-parameters.txt:
    amd_dynamic_epp=
    
> +
>  User Space Interface in ``sysfs`` - General
>  ===========================================
>  
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 26a8552581c57..7dd50b5825d78 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -1992,8 +1992,19 @@ static int __init amd_prefcore_param(char *str)
>  	return 0;
>  }
>  
> +static int __init amd_dynamic_epp_param(char *str)
> +{
> +	if (!strcmp(str, "disable"))
> +		dynamic_epp = false;
> +	if (!strcmp(str, "enable"))
> +		dynamic_epp = true;
> +
> +	return 0;
> +}
> +
>  early_param("amd_pstate", amd_pstate_param);
>  early_param("amd_prefcore", amd_prefcore_param);
> +early_param("amd_dynamic_epp", amd_dynamic_epp_param);
>  
>  MODULE_AUTHOR("Huang Rui <ray.huang@amd.com>");
>  MODULE_DESCRIPTION("AMD Processor P-state Frequency Driver");
> 
> -- 
> 2.43.0
> 

-- 
Thanks and Regards
gautham.