linux-kernel - Re: [PATCH v4 1/1] pwm: pca9685: fix gpio-only operation.

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Message-ID: <CAHp75VdaDP8GZGz5ZkKpSDdszjRzA+Miw=K7d_g3aeKTN4Ce=A@mail.gmail.com>
Date:   Thu, 20 Apr 2017 10:29:36 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Sven Van Asbroeck <thesven73@...il.com>
Cc:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Thierry Reding <thierry.reding@...il.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>, linux-pwm@...r.kernel.org,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Clemens Gruber <clemens.gruber@...ruber.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Sven Van Asbroeck <TheSven73@...glemail.com>
Subject: Re: [PATCH v4 1/1] pwm: pca9685: fix gpio-only operation.

On Tue, Apr 18, 2017 at 6:52 PM, Sven Van Asbroeck <thesven73@...il.com> wrote:
> Thanks for the feedback Andy !!

You're welcome.

>
>> I would go with
>>
>> /* Wait for @sleep microseconds for the oscillator to be back up */
>> if (sleep)
>>  udelay(sleep);
>>
>> Otherwise int sleep is oddly here.
>>
>> Or
>>
>> bool sleep
>>
>> /* Wait 500us ... */
>> if (sleep)
>>  udelay(500);
>>
>>> +}
>
> I think you may be getting confused between:
> - the chip's SLEEP bit (int sleep)
> - the amount of time to delay after chip comes _out of_ sleep.
> (always 500 us)
>
> If it's confusing for you, it might be confusing for others?
> Perhaps change the parameter to 'bool sleep_bit' or 'bool do_sleep'
> to make the distinction clearer?

Taking above into consideration perhaps sleep is not quite good word
at all. By functional description it sounds like latency tolerance to
me.

>> __maybe_unused and remove ugly #ifdef:ery.
>
> If this works on non- CONFIG_PM systems, I'm all for it !
> Grepping the drivers/ directory, I see that some drivers use
> #ifdef CONFIG_PM, some use __maybe_unused for runtime_pm.

This approach kinda new that's why you see variety of approaches.

> Mika and Thierry, thoughts ?

At the end it's Thierry's call, so, I'm not insisting.

-- 
With Best Regards,
Andy Shevchenko