linux-kernel - Re: [PATCH 4/4] cpufreq/amd-pstate: Drop needless EPP initialization

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Message-ID: <adf0c052-81f9-4a7f-939a-8a6f553721ca@amd.com>
Date: Tue, 15 Oct 2024 14:37:16 +0530
From: Dhananjay Ugwekar <Dhananjay.Ugwekar@....com>
To: Mario Limonciello <mario.limonciello@....com>,
 "Gautham R . Shenoy" <gautham.shenoy@....com>
Cc: Perry Yuan <perry.yuan@....com>, linux-kernel@...r.kernel.org,
 linux-pm@...r.kernel.org
Subject: Re: [PATCH 4/4] cpufreq/amd-pstate: Drop needless EPP initialization

Hello Mario,

On 10/12/2024 11:15 PM, Mario Limonciello wrote:
> The EPP value doesn't need to be cached to the CPPC request in
> amd_pstate_epp_update_limit() because it's passed as an argument
> at the end to amd_pstate_set_epp() and stored at that time.
> 

Tested this on an AMD Zen4 EPYC server system, ran some sanity tests, 
both modes (active and passive) seem to be working fine with the boost 
disabled and enabled.

You may add,
Tested-by: Dhananjay Ugwekar <dhananjay.ugwekar@....com>

Regards,
Dhananjay

> Signed-off-by: Mario Limonciello <mario.limonciello@....com>
> ---
>  drivers/cpufreq/amd-pstate.c | 6 ------
>  1 file changed, 6 deletions(-)
> 
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 8d2541f2c74b..90868c8b214e 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -1528,12 +1528,6 @@ static int amd_pstate_epp_update_limit(struct cpufreq_policy *policy)
>  	if (cpudata->policy == CPUFREQ_POLICY_PERFORMANCE)
>  		epp = 0;
>  
> -	/* Set initial EPP value */
> -	if (cpu_feature_enabled(X86_FEATURE_CPPC)) {
> -		value &= ~GENMASK_ULL(31, 24);
> -		value |= (u64)epp << 24;
> -	}
> -
>  	WRITE_ONCE(cpudata->cppc_req_cached, value);
>  	return amd_pstate_set_epp(cpudata, epp);
>  }