linux-kernel - Re: [PATCH] cpufreq: amd-pstate: Fix the inconsistency in max frequency units

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Date: Mon, 27 May 2024 09:40:21 -0500
From: Mario Limonciello <mario.limonciello@....com>
To: Dhananjay Ugwekar <Dhananjay.Ugwekar@....com>, rafael@...nel.org,
 ray.huang@....com, viresh.kumar@...aro.org, gautham.shenoy@....com
Cc: ananth.narayan@....com, linux-pm@...r.kernel.org,
 linux-kernel@...r.kernel.org, Perry.Yuan@....com
Subject: Re: [PATCH] cpufreq: amd-pstate: Fix the inconsistency in max
 frequency units

On 5/27/2024 00:11, Dhananjay Ugwekar wrote:
> The nominal frequency in cpudata is maintained in MHz whereas all other
> frequencies are in KHz. This means we have to convert nominal frequency
> value to KHz before we do any interaction with other frequency values.
> 
> In amd_pstate_set_boost(), this conversion from MHz to KHz is missed,
> fix that.
> 
> Tested on a AMD Zen4 EPYC server
> 
> Before:
> $ cat /sys/devices/system/cpu/cpufreq/policy*/scaling_max_freq | uniq
> 2151
> $ cat /sys/devices/system/cpu/cpufreq/policy*/cpuinfo_min_freq | uniq
> 400000
> $ cat /sys/devices/system/cpu/cpufreq/policy*/scaling_cur_freq | uniq
> 2151
> 409422
> 
> After:
> $ cat /sys/devices/system/cpu/cpufreq/policy*/scaling_max_freq | uniq
> 2151000
> $ cat /sys/devices/system/cpu/cpufreq/policy*/cpuinfo_min_freq | uniq
> 400000
> $ cat /sys/devices/system/cpu/cpufreq/policy*/scaling_cur_freq | uniq
> 2151000
> 1799527
> 

Cc: stable@...r.kernel.org

> Fixes: ec437d71db77 ("cpufreq: amd-pstate: Introduce a new AMD P-State driver to support future processors")
> Signed-off-by: Dhananjay Ugwekar <Dhananjay.Ugwekar@....com>

Acked-by: Mario Limonciello <mario.limonciello@....com>

> ---
>   drivers/cpufreq/amd-pstate.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 1b7e82a0ad2e..cde3b91b4422 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -669,7 +669,7 @@ static int amd_pstate_set_boost(struct cpufreq_policy *policy, int state)
>   	if (state)
>   		policy->cpuinfo.max_freq = cpudata->max_freq;
>   	else
> -		policy->cpuinfo.max_freq = cpudata->nominal_freq;
> +		policy->cpuinfo.max_freq = cpudata->nominal_freq * 1000;
>   
>   	policy->max = policy->cpuinfo.max_freq;
>