linux-kernel - Re: [PATCH 5/5] Documentation: add amd-pstate kernel command line options

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Message-ID: <Y3W1uHu/GMHu5LUY@BLR-5CG11610CF.amd.com>
Date:   Thu, 17 Nov 2022 09:46:56 +0530
From:   "Gautham R. Shenoy" <gautham.shenoy@....com>
To:     Perry Yuan <Perry.Yuan@....com>
Cc:     rafael.j.wysocki@...el.com, ray.huang@....com,
        viresh.kumar@...aro.org, Mario.Limonciello@....com,
        Nathan.Fontenot@....com, Alexander.Deucher@....com,
        Deepak.Sharma@....com, Shimmer.Huang@....com, Li.Meng@....com,
        Xiaojian.Du@....com, wyes.karny@....com, ananth.narayan@....com,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/5] Documentation: add amd-pstate kernel command line
 options

On Thu, Nov 17, 2022 at 10:49:55AM +0800, Perry Yuan wrote:
> Add a new amd pstate driver command line option to enable driver passive
> working mode via MSR and shared memory interface to request desired
> performance within abstract scale and the power management firmware
> (SMU) convert the perf requests into actual hardware pstates.
> 
> Also the `disable` parameter can disable the pstate driver loading by
> adding `amd_pstate=disable` to kernel command line.
> 
> Signed-off-by: Perry Yuan <Perry.Yuan@....com>

Reviewed-by: Gautham R. Shenoy <gautham.shenoy@....com>

> ---
>  Documentation/admin-guide/kernel-parameters.txt | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index a465d5242774..42af9ca0127e 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -6959,3 +6959,14 @@
>  				memory, and other data can't be written using
>  				xmon commands.
>  			off	xmon is disabled.
> +
> +	amd_pstate=	[X86]
> +			disable
> +			  Do not enable amd_pstate as the default
> +			  scaling driver for the supported processors
> +			passive
> +			  Use amd_pstate as a scaling driver, driver requests a
> +			  desired performance on this abstract scale and the power
> +			  management firmware translates the requests into actual
> +			  hardware states (core frequency, data fabric and memory
> +			  clocks etc.)
> -- 
> 2.25.1
>