linux-kernel - Re: [PATCH v4 19/19] cpufreq/amd-pstate: Drop amd_pstate_epp_cpu

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Message-ID: <32d21c7a-9714-4f53-ad77-22ab81152455@amd.com>
Date: Mon, 24 Feb 2025 14:55:37 +0530
From: Dhananjay Ugwekar <Dhananjay.Ugwekar@....com>
To: Mario Limonciello <superm1@...nel.org>,
 "Gautham R . Shenoy" <gautham.shenoy@....com>,
 Perry Yuan <perry.yuan@....com>
Cc: "open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
 <linux-kernel@...r.kernel.org>,
 "open list:CPU FREQUENCY SCALING FRAMEWORK" <linux-pm@...r.kernel.org>,
 Mario Limonciello <mario.limonciello@....com>
Subject: Re: [PATCH v4 19/19] cpufreq/amd-pstate: Drop
 amd_pstate_epp_cpu_offline()

On 2/20/2025 2:33 AM, Mario Limonciello wrote:
> From: Mario Limonciello <mario.limonciello@....com>
> 
> When the CPU goes offline there is no need to change the CPPC request
> because the CPU will go into the deepest C-state it supports already.> 
> Actually changing the CPPC request when it goes offline messes up the
> cached values and can lead to the wrong values being restored when
> it comes back.
> 
> Instead if the CPU comes back online let amd_pstate_epp_set_policy()
> restore it to expected values.

Small suggestion below, apart from that LGTM

Reviewed-by: Dhananjay Ugwekar <dhananjay.ugwekar@....com>

> 
> Signed-off-by: Mario Limonciello <mario.limonciello@....com>
> ---
>  drivers/cpufreq/amd-pstate.c | 9 +--------
>  1 file changed, 1 insertion(+), 8 deletions(-)
> 
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 408e63aff377a..5068778c1542a 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -1610,14 +1610,7 @@ static int amd_pstate_epp_cpu_online(struct cpufreq_policy *policy)
>  
>  static int amd_pstate_epp_cpu_offline(struct cpufreq_policy *policy)
>  {
> -	struct amd_cpudata *cpudata = policy->driver_data;
> -	union perf_cached perf = READ_ONCE(cpudata->perf);
> -
> -	if (cpudata->suspended)
> -		return 0;
> -
> -	return amd_pstate_update_perf(policy, perf.lowest_perf, 0, perf.lowest_perf,
> -				      AMD_CPPC_EPP_BALANCE_POWERSAVE, false);
> +	return 0;

Instead of making it an empty "return 0" function, can we remove this 
callback altogether? Didnt check if there are any constraints against 
removing it.

>  }
>  
>  static int amd_pstate_epp_suspend(struct cpufreq_policy *policy)