Re: [PATCH 4/6] iio: proximity: srf04: Use pm_ptr() to remove unused struct dev_pm_ops

From: Paul Cercueil <paul@crapouillou.net>
To: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Jonathan Cameron <jic23@kernel.org>,
	linux-iio <linux-iio@vger.kernel.org>,
	Gwendal Grignou <gwendal@chromium.org>,
	Andreas Klinger <ak@it-klinger.de>,
	LI Qingwu <Qing-wu.Li@leica-geosystems.com.cn>,
	Mike Looijmans <mike.looijmans@topic.nl>,
	Lorenzo Bianconi <lorenzo.bianconi83@gmail.com>,
	Jonathan Cameron <Jonathan.Cameron@huawei.com>
Subject: Re: [PATCH 4/6] iio: proximity: srf04: Use pm_ptr() to remove unused struct dev_pm_ops
Date: Mon, 08 Aug 2022 11:49:15 +0200	[thread overview]
Message-ID: <3AJAGR.1Z7AWJJTEDPB1@crapouillou.net> (raw)
In-Reply-To: <CAHp75VeEtkSUioMLafQuS+kiyEU71SEjcMj8ZLUEv_AJk2mx+g@mail.gmail.com>

Le lun., août 8 2022 at 11:39:56 +0200, Andy Shevchenko 
<andy.shevchenko@gmail.com> a écrit :
> On Mon, Aug 8, 2022 at 11:35 AM Paul Cercueil <paul@crapouillou.net> 
> wrote:
>>  Le lun., août 8 2022 at 11:28:12 +0200, Andy Shevchenko
>>  <andy.shevchenko@gmail.com> a écrit :
>>  > On Sun, Aug 7, 2022 at 8:46 PM Jonathan Cameron <jic23@kernel.org>
>>  > wrote:
> 
> ...
> 
>>  >>  In this case we can't simply use DEFINE_RUNTIME_DEV_PM_OPS() 
>> because
>>  >>  that would provide suspend and resume functions without the
>>  >>  checks the driver is doing before calling runtime_pm functions
>>  >>  (whether the necessary GPIO is provided).  It may be possible to
>>  >>  clean that up in future by moving the checks into the callbacks.
>>  >
>>  > ...
>>  >
>>  >>   static const struct dev_pm_ops srf04_pm_ops = {
>>  >>  -       SET_RUNTIME_PM_OPS(srf04_pm_runtime_suspend,
>>  >>  -                               srf04_pm_runtime_resume, NULL)
>>  >>  +       RUNTIME_PM_OPS(srf04_pm_runtime_suspend,
>>  >>  +                      srf04_pm_runtime_resume, NULL)
>>  >>   };
>>  >
>>  > static DEFINE_RUNTIME_DEV_PM_OPS(...);
>>  >
>>  > ?
>> 
>>  Read the commit message?
> 
> Yes, and I'm not sure how that part is relevant. The callbacks won't
> be called if pm_ptr() equals no-op, no?

Have a look at the definition of DEFINE_RUNTIME_DEV_PM_OPS(). I believe 
it does not do what you think it does.

What the commit message says is that using DEFINE_RUNTIME_DEV_PM_OPS() 
would add .suspend/.resume callbacks, which aren't provided with the 
current code.

Cheers,
-Paul