linux-kernel - Re: [PATCH v2 1/3] cpufreq: CPPC: Add cppc_cpufreq_search_cpu

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Message-ID: <a6bea108-5e3b-be13-5852-4607544985a2@arm.com>
Date:   Mon, 11 Apr 2022 12:34:18 +0200
From:   Pierre Gondois <pierre.gondois@....com>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     linux-kernel@...r.kernel.org, Ionela.Voinescu@....com,
        Lukasz.Luba@....com, Morten.Rasmussen@....com,
        Dietmar.Eggemann@....com, maz@...nel.org,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Ard Biesheuvel <ardb@...nel.org>,
        Fuad Tabba <tabba@...gle.com>,
        Valentin Schneider <valentin.schneider@....com>,
        Rob Herring <robh@...nel.org>,
        linux-arm-kernel@...ts.infradead.org, linux-pm@...r.kernel.org
Subject: Re: [PATCH v2 1/3] cpufreq: CPPC: Add cppc_cpufreq_search_cpu_data



On 4/11/22 05:10, Viresh Kumar wrote:
> On 07-04-22, 10:16, Pierre Gondois wrote:
>> From: Pierre Gondois <Pierre.Gondois@....com>
>>
>> cppc_cpufreq_get_cpu_data() allocates a new struct cppc_cpudata
>> for the input CPU at each call.
>>
>> To search the struct associated with a cpu without allocating
>> a new one, add cppc_cpufreq_search_cpu_data().
>> Also add an early prototype.
>>
>> This will be used in a later patch, when generating artificial
>> performance states to register an artificial Energy Model in the
>> cppc_cpufreq driver and enable the Energy Aware Scheduler for ACPI
>> based systems.
>>
>> Signed-off-by: Pierre Gondois <Pierre.Gondois@....com>
>> ---
>>   drivers/cpufreq/cppc_cpufreq.c | 15 +++++++++++++++
>>   1 file changed, 15 insertions(+)
>>
>> diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c
>> index 82d370ae6a4a..ffcd9704add2 100644
>> --- a/drivers/cpufreq/cppc_cpufreq.c
>> +++ b/drivers/cpufreq/cppc_cpufreq.c
>> @@ -41,6 +41,8 @@
>>    */
>>   static LIST_HEAD(cpu_data_list);
>>   
>> +static struct cppc_cpudata *cppc_cpufreq_search_cpu_data(unsigned int cpu);
>> +
>>   static bool boost_supported;
>>   
>>   struct cppc_workaround_oem_info {
>> @@ -479,6 +481,19 @@ static void cppc_cpufreq_put_cpu_data(struct cpufreq_policy *policy)
>>   	policy->driver_data = NULL;
>>   }
>>   
>> +static struct cppc_cpudata *
>> +cppc_cpufreq_search_cpu_data(unsigned int cpu)
>> +{
>> +	struct cppc_cpudata *iter, *tmp;
>> +
>> +	list_for_each_entry_safe(iter, tmp, &cpu_data_list, node) {
>> +		if (cpumask_test_cpu(cpu, iter->shared_cpu_map))
>> +			return iter;
>> +	}
>> +
>> +	return NULL;
>> +}
> 
> Did you miss this in cppc_cpufreq_cpu_init() ?
> 
> 	policy->driver_data = cpu_data;
> 
> The data is saved inside the policy and it shouldn't be difficult to
> fetch it from there, instead of going through the list.
> 

A previous (internal) implementation required this function,
but this is not necessary anymore indeed. I will drop this patch,
Thanks for the review,
Pierre