linux-kernel - Re: [PATCH v2] PM / devfreq: tegra30: Make CPUFreq notifier to take into account boosting

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Date:   Fri, 3 Apr 2020 15:20:55 +0900
From:   Chanwoo Choi <cw00.choi@...sung.com>
To:     Dmitry Osipenko <digetx@...il.com>,
        Thierry Reding <thierry.reding@...il.com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        Jonathan Hunter <jonathanh@...dia.com>
Cc:     linux-pm@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] PM / devfreq: tegra30: Make CPUFreq notifier to take
 into account boosting

On 4/3/20 7:24 AM, Dmitry Osipenko wrote:
> We're taking into account both HW memory-accesses + CPU activity based on
> current CPU's frequency. For memory-accesses there is a kind of hysteresis
> in a form of "boosting" which is managed by the tegra30-devfreq driver.
> If current HW memory activity is higher than activity judged based of the
> CPU's frequency, then there is no need to schedule cpufreq_update_work
> because the result of the work will be a NO-OP. And thus,
> tegra_actmon_cpufreq_contribution() should return 0, meaning that at the
> moment CPU frequency doesn't contribute anything to the final decision
> about required memory clock rate.
> 
> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
> ---
> 
> Changelog:
> 
> v2: - Made commit's message more detailed, which was requested by Chanwoo Choi
>       in the review comment to v1.
> 
>     - This patch is now made to be standalone because there are no dependencies
>       in regards to this change.
> 
>  drivers/devfreq/tegra30-devfreq.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/devfreq/tegra30-devfreq.c b/drivers/devfreq/tegra30-devfreq.c
> index 28b2c7ca416e..dfc3ac93c584 100644
> --- a/drivers/devfreq/tegra30-devfreq.c
> +++ b/drivers/devfreq/tegra30-devfreq.c
> @@ -420,7 +420,7 @@ tegra_actmon_cpufreq_contribution(struct tegra_devfreq *tegra,
>  
>  	static_cpu_emc_freq = actmon_cpu_to_emc_rate(tegra, cpu_freq);
>  
> -	if (dev_freq >= static_cpu_emc_freq)
> +	if (dev_freq + actmon_dev->boost_freq >= static_cpu_emc_freq)
>  		return 0;
>  
>  	return static_cpu_emc_freq;
> 

Applied it. Thanks.

-- 
Best Regards,
Chanwoo Choi
Samsung Electronics