linux-kernel - Re: [RFC PATCH 2/3] cpufreq: Add SW BOOST support for drivers without frequency table

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Date:   Thu, 14 May 2020 16:16:29 +0200
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Xiongfeng Wang <wangxiongfeng2@...wei.com>
Cc:     viresh.kumar@...aro.org, Souvik.Chakravarty@....com,
        Thanu.Rangarajan@....com, Sudeep.Holla@....com,
        guohanjun@...wei.com, john.garry@...wei.com,
        jonathan.cameron@...wei.com, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 2/3] cpufreq: Add SW BOOST support for drivers without frequency table

On Friday, May 8, 2020 11:11:03 AM CEST Xiongfeng Wang wrote:
> Software-managed BOOST get the boost frequency by check the flag
> CPUFREQ_BOOST_FREQ at driver's frequency table. But some cpufreq driver
> don't have frequency table and use other methods to get the frequency
> range, such CPPC cpufreq driver.
> 
> To add SW BOOST support for drivers without frequency table, we add
> members in 'cpufreq_policy.cpufreq_cpuinfo' to record the max frequency
> of boost mode and non-boost mode. The cpufreq driver initialize these two
> members when probing.
> 
> Signed-off-by: Xiongfeng Wang <wangxiongfeng2@...wei.com>
> ---
>  drivers/cpufreq/cpufreq.c | 23 +++++++++++++++--------
>  include/linux/cpufreq.h   |  2 ++
>  2 files changed, 17 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index 475fb1b..a299426 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -2508,15 +2508,22 @@ static int cpufreq_boost_set_sw(int state)
>  	int ret = -EINVAL;
>  
>  	for_each_active_policy(policy) {
> -		if (!policy->freq_table)
> -			continue;
> -
> -		ret = cpufreq_frequency_table_cpuinfo(policy,
> +		if (policy->freq_table) {
> +			ret = cpufreq_frequency_table_cpuinfo(policy,
>  						      policy->freq_table);
> -		if (ret) {
> -			pr_err("%s: Policy frequency update failed\n",
> -			       __func__);
> -			break;
> +			if (ret) {
> +				pr_err("%s: Policy frequency update failed\n",
> +				       __func__);
> +				break;
> +			}
> +		} else if (policy->cpuinfo.boost_max_freq) {
> +			if (state)
> +				policy->max = policy->cpuinfo.boost_max_freq;
> +			else
> +				policy->max = policy->cpuinfo.nonboost_max_freq;
> +			policy->cpuinfo.max_freq = policy->max;
> +		} else {
> +			continue;
>  		}

Why do you need to update this function?

The driver should be able to provide its own ->set_boost callback just fine,
shouldn't it?

>  
>  		ret = freq_qos_update_request(policy->max_freq_req, policy->max);
> diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
> index 018dce8..c3449e6 100644
> --- a/include/linux/cpufreq.h
> +++ b/include/linux/cpufreq.h
> @@ -43,6 +43,8 @@ enum cpufreq_table_sorting {
>  struct cpufreq_cpuinfo {
>  	unsigned int		max_freq;
>  	unsigned int		min_freq;
> +	unsigned int		boost_max_freq;
> +	unsigned int		nonboost_max_freq;
>  
>  	/* in 10^(-9) s = nanoseconds */
>  	unsigned int		transition_latency;
>