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Date:   Thu, 7 Jul 2022 14:56:58 -0500
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Subject: Re: [PATCH 07/12] cpufreq: amd_pstate: map desired perf into pstate
 scope for powersave governor
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To:     Perry Yuan <Perry.Yuan@amd.com>, rafael.j.wysocki@intel.com,
        viresh.kumar@linaro.org, Ray.Huang@amd.com,
        "Rafael J. Wysocki" <rafael@kernel.org>, linux-pm@vger.kernel.org,
        linux-kernel@vger.kernel.org
Cc:     Deepak.Sharma@amd.com, Mario.Limonciello@amd.com,
        Nathan.Fontenot@amd.com, Alexander.Deucher@amd.com,
        Jinzhou.Su@amd.com, Xinmei.Huang@amd.com, Xiaojian.Du@amd.com,
        Li.Meng@amd.com
References: <20220707170022.216202-1-Perry.Yuan@amd.com>
From:   Nathan Fontenot <nafonten@amd.com>
In-Reply-To: <20220707170022.216202-1-Perry.Yuan@amd.com>
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On 7/7/22 12:00, Perry Yuan 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@amd.com>
> ---
>  drivers/cpufreq/amd-pstate.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 7c51f4125263..154eed849f38 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -317,6 +317,7 @@ static int amd_pstate_target(struct cpufreq_policy *policy,
>  	des_perf = DIV_ROUND_CLOSEST(target_freq * cap_perf,
>  				     cpudata->max_freq);
>  
> +	des_perf = clamp_t(unsigned long, des_perf, min_perf, max_perf);
>  	cpufreq_freq_transition_begin(policy, &freqs);
>  	amd_pstate_update(cpudata, min_perf, des_perf,
>  			  max_perf, false);

The clamping of the desired perf value should be moved to amd_pstate_update(). The
only other caller of amd_pstate_update() is amd_pstate_adjust_perf() which already
clamps the desired perf value before making the call.

-Nathan