linux-kernel - Re: [PATCH] cpufreq: CPPC: Correct desired

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Message-ID: <CAFHUOYyBZXKuVusNf4jy17cnY9zj9g5AacZYDO3x-y31J7oRmg@mail.gmail.com>
Date:   Tue, 11 Oct 2016 15:31:36 -0700
From:   Hoan Tran <hotran@....com>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:     Viresh Kumar <viresh.kumar@...aro.org>,
        Prashanth Prakash <pprakash@...eaurora.org>,
        Al Stone <ahs3@...hat.com>, linux-pm@...r.kernel.org,
        lkml <linux-kernel@...r.kernel.org>, Loc Ho <lho@....com>,
        Duc Dang <dhdang@....com>
Subject: Re: [PATCH] cpufreq: CPPC: Correct desired_perf calculation

Hi Rafael,

On Tue, Oct 11, 2016 at 2:50 PM, Rafael J. Wysocki <rjw@...ysocki.net> wrote:
> On Tuesday, October 11, 2016 02:12:00 PM Hoan Tran wrote:
>> The desired_perf is an abstract performance number. Its value should
>> be in the range of [lowest perf, highest perf] of CPPC.
>> The correct calculation is
>>   desired_perf = freq * cppc_highest_perf / cppc_dmi_max_khz
>>
>> Signed-off-by: Hoan Tran <hotran@....com>
>> ---
>>  drivers/cpufreq/cppc_cpufreq.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c
>> index 1b2f28f..ab1d4b7 100644
>> --- a/drivers/cpufreq/cppc_cpufreq.c
>> +++ b/drivers/cpufreq/cppc_cpufreq.c
>> @@ -84,7 +84,7 @@ static int cppc_cpufreq_set_target(struct cpufreq_policy *policy,
>>
>>       cpu = all_cpu_data[policy->cpu];
>>
>> -     cpu->perf_ctrls.desired_perf = (u64)target_freq * policy->max / cppc_dmi_max_khz;
>> +     cpu->perf_ctrls.desired_perf = (u64)target_freq * cpu->perf_caps.highest_perf / cppc_dmi_max_khz;
>>       freqs.old = policy->cur;
>>       freqs.new = target_freq;
>>
>>
>
> This patch has already been applied AFAICS.
>

You mean this applied patch "cpufreq: CPPC: Avoid overflow when
calculating desired_perf"

This is another the bug, not the overflow bug.

Thanks
Hoan



> Thanks,
> Rafael
>