linux-kernel - Re: [PATCH 4/7] cpufreq: amd-pstate: fix max_perf calculation for amd_get_max

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Date: Fri, 26 Jan 2024 09:54:26 -0600
From: Mario Limonciello <mario.limonciello@....com>
To: Perry Yuan <perry.yuan@....com>, rafael.j.wysocki@...el.com,
 viresh.kumar@...aro.org, Ray.Huang@....com, gautham.shenoy@....com,
 Borislav.Petkov@....com
Cc: Alexander.Deucher@....com, Xinmei.Huang@....com, Xiaojian.Du@....com,
 Li.Meng@....com, linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/7] cpufreq: amd-pstate: fix max_perf calculation for
 amd_get_max_freq()

On 1/26/2024 02:08, Perry Yuan wrote:
> From: Perry Yuan <Perry.Yuan@....com>
> 
> When CPU core Precision Boost state changed, the max frequency will also
> need to be updated according to the current boost state, if boost is
> disabled now, the max perf will be limited to nominal perf values.
> otherwise the max frequency will be showed wrongly.

What about the previous cppc_req?  Shouldn't it be explicitly updated as 
a result of this too?

> 
> Signed-off-by: Perry Yuan <Perry.Yuan@....com>
> ---
>   drivers/cpufreq/amd-pstate.c | 4 ++++
>   1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index b37bea7440b9..3286d72f375e 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -599,6 +599,10 @@ static int amd_get_max_freq(struct amd_cpudata *cpudata)
>   	nominal_perf = READ_ONCE(cpudata->nominal_perf);
>   	max_perf = READ_ONCE(cpudata->highest_perf);
>   
> +	/* when boost is off, the highest perf will be limited to nominal_perf */
> +	if (!global.cpb_boost)
> +		max_perf = nominal_perf;
> +
>   	boost_ratio = div_u64(max_perf << SCHED_CAPACITY_SHIFT,
>   			      nominal_perf);
>