linux-kernel - Re: [TEGRA194_CPUFREQ Patch 2/3] cpufreq: Add Tegra194 cpufreq driver

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Message-ID: <8ea80551-b47c-3dd5-4efa-6befecc279e1@nvidia.com>
Date:   Thu, 16 Apr 2020 12:36:30 +0530
From:   Sumit Gupta <sumitg@...dia.com>
To:     Viresh Kumar <viresh.kumar@...aro.org>
CC:     <rjw@...ysocki.net>, <catalin.marinas@....com>, <will@...nel.org>,
        <thierry.reding@...il.com>, <jonathanh@...dia.com>,
        <talho@...dia.com>, <linux-pm@...r.kernel.org>,
        <linux-tegra@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <bbasu@...dia.com>,
        <mperttunen@...dia.com>, Sumit Gupta <sumitg@...dia.com>
Subject: Re: [TEGRA194_CPUFREQ Patch 2/3] cpufreq: Add Tegra194 cpufreq driver



On 16/04/20 9:07 AM, Viresh Kumar wrote:
> External email: Use caution opening links or attachments
> 
> 
> On 15-04-20, 16:55, Sumit Gupta wrote:
>>
>>
>> On 14/04/20 11:15 AM, Viresh Kumar wrote:
>>> External email: Use caution opening links or attachments
>>>
>>>
>>> On 13-04-20, 17:50, Sumit Gupta wrote:
>>>> This was done considering long delay value as explained previously.
>>>> Do you think that smp_call_function_single() would be better than work queue
>>>> here?
>>>
>>> Don't work with assumptions, you should test both and see which one
>>> works better. Workqueue should never be faster than
>>> smp_call_function_single() with my understanding.
>> Checked the time taken and its almost same in both cases.
>> Earlier we used smp_call_function_single(), but delay time period was small
>> in that SOC. In T194, the time period was more. So, this is an optimization
>> done because using work queue has advantage as interrupts will not be
>> disabled for that period.
> 
> Hmm, okay, keep the workqueue and mention the required details in a
> comment for everyone to understand why the implementation is done that
> way.
> 

sure, thank you!

> --
> viresh
>