linux-kernel - Re: [PATCH v4 07/13] cpufreq: amd_pstate: map desired perf into pstate scope for powersave governor

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Date:   Tue, 19 Jul 2022 08:56:19 +0800
From:   Huang Rui <ray.huang@....com>
To:     "Yuan, Perry" <Perry.Yuan@....com>
Cc:     "rafael.j.wysocki@...el.com" <rafael.j.wysocki@...el.com>,
        "viresh.kumar@...aro.org" <viresh.kumar@...aro.org>,
        "Sharma, Deepak" <Deepak.Sharma@....com>,
        "Limonciello, Mario" <Mario.Limonciello@....com>,
        "Fontenot, Nathan" <Nathan.Fontenot@....com>,
        "Deucher, Alexander" <Alexander.Deucher@....com>,
        "Su, Jinzhou (Joe)" <Jinzhou.Su@....com>,
        "Huang, Shimmer" <Shimmer.Huang@....com>,
        "Du, Xiaojian" <Xiaojian.Du@....com>,
        "Meng, Li (Jassmine)" <Li.Meng@....com>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 07/13] cpufreq: amd_pstate: map desired perf into
 pstate scope for powersave governor

On Fri, Jul 15, 2022 at 06:04:26PM +0800, Yuan, Perry wrote:
> The patch will fix the invalid desired perf value for powersave
> governor. This issue is found when testing on one AMD EPYC system, the
> actual des_perf is smaller than the min_perf value, that is invalid
> value. because the min_perf is the lowest_perf system can support in
> idle state.
> 
> Signed-off-by: Perry Yuan <Perry.Yuan@....com>

Reviewed-by: Huang Rui <ray.huang@....com>

> ---
>  drivers/cpufreq/amd-pstate.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 4b764870035e..ebc7c6d389be 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -268,6 +268,7 @@ static void amd_pstate_update(struct amd_cpudata *cpudata, u32 min_perf,
>  	u64 prev = READ_ONCE(cpudata->cppc_req_cached);
>  	u64 value = prev;
>  
> +	des_perf = clamp_t(unsigned long, des_perf, min_perf, max_perf);
>  	value &= ~AMD_CPPC_MIN_PERF(~0L);
>  	value |= AMD_CPPC_MIN_PERF(min_perf);
>  
> @@ -356,8 +357,6 @@ static void amd_pstate_adjust_perf(unsigned int cpu,
>  	if (max_perf < min_perf)
>  		max_perf = min_perf;
>  
> -	des_perf = clamp_t(unsigned long, des_perf, min_perf, max_perf);
> -
>  	amd_pstate_update(cpudata, min_perf, des_perf, max_perf, true);
>  }
>  
> -- 
> 2.32.0
>