linux-kernel - Re: [PATCH] cpufreq: scmi: Fix frequency invariance in slow path

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Date:   Wed, 9 Jan 2019 16:15:11 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Quentin Perret <quentin.perret@....com>
Cc:     sudeep.holla@....com, rjw@...ysocki.net,
        linux-arm-kernel@...ts.infradead.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, dietmar.eggemann@....com,
        qais.yousef@....com
Subject: Re: [PATCH] cpufreq: scmi: Fix frequency invariance in slow path

On 09-01-19, 10:42, Quentin Perret wrote:
> The scmi-cpufreq driver calls the arch_set_freq_scale() callback on
> frequency changes to provide scale-invariant load-tracking signals to
> the scheduler. However, in the slow path, it does so while specifying
> the current and max frequencies in different units, hence resulting in a
> broken freq_scale factor.
> 
> Fix this by passing all frequencies in KHz, as stored in the CPUFreq
> frequency table.
> 
> Fixes: 99d6bdf33877 ("cpufreq: add support for CPU DVFS based on SCMI
> message protocol")
> Signed-off-by: Quentin Perret <quentin.perret@....com>
> ---
>  drivers/cpufreq/scmi-cpufreq.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/cpufreq/scmi-cpufreq.c b/drivers/cpufreq/scmi-cpufreq.c
> index 50b1551ba894..3f0693439486 100644
> --- a/drivers/cpufreq/scmi-cpufreq.c
> +++ b/drivers/cpufreq/scmi-cpufreq.c
> @@ -52,9 +52,9 @@ scmi_cpufreq_set_target(struct cpufreq_policy *policy, unsigned int index)
>  	int ret;
>  	struct scmi_data *priv = policy->driver_data;
>  	struct scmi_perf_ops *perf_ops = handle->perf_ops;
> -	u64 freq = policy->freq_table[index].frequency * 1000;
> +	u64 freq = policy->freq_table[index].frequency;
>  
> -	ret = perf_ops->freq_set(handle, priv->domain_id, freq, false);
> +	ret = perf_ops->freq_set(handle, priv->domain_id, freq * 1000, false);
>  	if (!ret)
>  		arch_set_freq_scale(policy->related_cpus, freq,
>  				    policy->cpuinfo.max_freq);

Acked-by: Viresh Kumar <viresh.kumar@...aro.org>

-- 
viresh