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

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Date:   Tue, 19 May 2020 09:04:33 +0800
From:   Xiongfeng Wang <wangxiongfeng2@...wei.com>
To:     Viresh Kumar <viresh.kumar@...aro.org>
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

Hi Viresh,

Thanks for your reply !

On 2020/5/18 15:53, Viresh Kumar wrote:
> 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.

Thanks for your advice. It's a good idea. I will change it in the next version.

Thanks,
Xiongfeng

>