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

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Date: Mon, 27 May 2024 21:15:29 +0530
From: "Gautham R. Shenoy" <gautham.shenoy@....com>
To: Mario Limonciello <mario.limonciello@....com>
Cc: Dhananjay Ugwekar <Dhananjay.Ugwekar@....com>, rafael@...nel.org,
	ray.huang@....com, viresh.kumar@...aro.org, 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 Mon, May 27, 2024 at 09:40:21AM -0500, Mario Limonciello wrote:
> 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>

Acked-by: Gautham R. Shenoy <gautham.shenoy@....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;
>