linux-kernel - Re: [PATCH V2 1/2] ACPI: processor_perflib: Simplify code and stop using CPUFREQ

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Date:   Mon, 30 Jan 2017 08:49:06 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     Viresh Kumar <viresh.kumar@...aro.org>,
        Rafael Wysocki <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>,
        Lists linaro-kernel <linaro-kernel@...ts.linaro.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>
Subject: Re: [PATCH V2 1/2] ACPI: processor_perflib: Simplify code and stop
 using CPUFREQ_START

On Mon, Jan 30, 2017 at 8:07 AM, Rafael J. Wysocki <rafael@...nel.org> wrote:
> On Mon, Jan 30, 2017 at 5:29 AM, Viresh Kumar <viresh.kumar@...aro.org> wrote:
>> acpi_processor_ppc_notifier() can live without using CPUFREQ_START
>> (which is gonna be removed soon), as it is only used while setting
>> ignore_ppc to 0. This can be done with the help of "ignore_ppc < 0"
>> check alone. The notifier function anyway ignores all events except
>> CPUFREQ_ADJUST and dropping CPUFREQ_START wouldn't harm at all.
>>
>> Once CPUFREQ_START event is removed from the cpufreq core,
>> acpi_processor_ppc_notifier() will get called only for CPUFREQ_NOTIFY or
>> CPUFREQ_ADJUST event. Drop the return statement from the first if block
>> to make sure we don't ignore any such events.
>>
>> Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
>>
>> ---
>> V1->V2:
>> - Improved changelog
>> - Don't move the first if block to a later point, as it becomes useless
>>   then.
>> ---
>>  drivers/acpi/processor_perflib.c | 4 +---
>>  1 file changed, 1 insertion(+), 3 deletions(-)
>>
>> diff --git a/drivers/acpi/processor_perflib.c b/drivers/acpi/processor_perflib.c
>> index f0b4a981b8d3..18b72eec3507 100644
>> --- a/drivers/acpi/processor_perflib.c
>> +++ b/drivers/acpi/processor_perflib.c
>> @@ -75,10 +75,8 @@ static int acpi_processor_ppc_notifier(struct notifier_block *nb,
>>         struct acpi_processor *pr;
>>         unsigned int ppc = 0;
>>
>> -       if (event == CPUFREQ_START && ignore_ppc <= 0) {
>> +       if (ignore_ppc < 0)
>>                 ignore_ppc = 0;
>> -               return 0;
>> -       }
>
> Don't we want to return from here if ignore_ppc is 0?

I actually wanted to say "was negative" here, not sure why I said the
above in the end.

Anyway, the patch looks correct now.

Thanks,
Rafael