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

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Message-ID: <20200518075309.xoon4vyfjywmteww@vireshk-i7>
Date:   Mon, 18 May 2020 13:23:09 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Xiongfeng Wang <wangxiongfeng2@...wei.com>
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        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

Sorry for the delay from my side in replying to this thread.

On 15-05-20, 09:49, Xiongfeng Wang wrote:
> On 2020/5/14 22:16, Rafael J. Wysocki wrote:
> > 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?
> 
> My original thought is to reuse the current SW BOOST code as possible, but this
> seems to change the cpufreq core too much.
> 
> Thanks for your advice. This is better. I will provide a '->set_boost' callback
> for CPPC driver. But I will need to export 'cpufreq_policy_list' and make the
> macro 'for_each_active_policy' public.

This can and should be avoided, I will rather move the for-each-policy
loop in cpufreq_boost_trigger_state() and call ->set_boost() for each
policy and pass policy as argument as well. You would be required to
update existing users of sw boost.

-- 
viresh