Re: [PATCH 00/49] iio: Tree wide switch from CONFIG_PM* to __maybe_unused etc.

From: Arnd Bergmann <arnd@arndb.de>
To: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Arnd Bergmann <arnd@arndb.de>,
	Paul Cercueil <paul@crapouillou.net>,
	Jonathan Cameron <jic23@kernel.org>,
	linux-iio@vger.kernel.org, Lars-Peter Clausen <lars@metafoo.de>,
	Alexandre Belloni <alexandre.belloni@bootlin.com>,
	Anson Huang <anson.huang@nxp.com>,
	Brian Masney <masneyb@onstation.org>,
	Fabrice Gasnier <fabrice.gasnier@foss.st.com>,
	Hans de Goede <hdegoede@redhat.com>,
	Heiko Stuebner <heiko.stuebner@theobroma-systems.com>,
	Icenowy Zheng <icenowy@aosc.io>,
	Jonathan Albrieux <jonathan.albrieux@gmail.com>,
	Krzysztof Kozlowski <krzk@kernel.org>,
	Linus Walleij <linus.walleij@linaro.org>,
	Luca Weiss <luca@z3ntu.xyz>,
	Ludovic Desroches <ludovic.desroches@microchip.com>,
	Manivannan Sadhasivam <mani@kernel.org>,
	Martijn Braam <martijn@brixit.nl>,
	Maslov Dmitry <maslovdmitry@seeed.cc>,
	Olivier Moysan <olivier.moysan@foss.st.com>,
	Stefan-Gabriel Mirea <stefan-gabriel.mirea@nxp.com>,
	Vaishnav M A <vaishnav@beagleboard.org>
Subject: Re: [PATCH 00/49] iio: Tree wide switch from CONFIG_PM* to __maybe_unused etc.
Date: Wed, 24 Nov 2021 13:23:47 +0100	[thread overview]
Message-ID: <CAK8P3a1OmBT2xNTHVp8f3=4TtwtC+6cvn27PCF-j0MMAriK+Hg@mail.gmail.com> (raw)
In-Reply-To: <20211124101113.000033c6@Huawei.com>

On Wed, Nov 24, 2021 at 11:11 AM Jonathan Cameron
<Jonathan.Cameron@huawei.com> wrote:
> On Wed, 24 Nov 2021 08:29:40 +0100 Arnd Bergmann <arnd@arndb.de> wrote:
> >
> > > The problem then is that the SET_*_PM_OPS macros are defined
> > > differently according to CONFIG_PM, so their definition would need to
> > > be changed to use the (redefined) pm_ptr() macro and a corresponding
> > > pm_sleep_ptr() macro. Unfortunately since the SET_*_PM_OPS macros are
> > > used everywhere with code wrapped around #ifdef CONFIG_PM guards, it
> > > wouldn't be easy to change them, and it would just be easier to
> > > introduce new macros.
> >
> > Right, this is what we've discussed multiple times, and I think everyone
> > agreed we should do this, but so far we could not come up with a name
> > for the new macro, and changing the macro in place is not practical unless
> > we change hundreds of drivers in the same way as the iio series first.
>
> Nasty indeed and I'm not sure how scriptable either as lots of subtle variants
> unfortunately.

The minor variants (late, noirq) are actually the easy part, for the macros that
have fewer users, we can just have one patch per macro that changes it treewide.
For SET_SYSTEM_SLEEP_PM_OPS/SET_RUNTIME_PM_OPS and their
DEV_PM_OPS variants, this would be a lot harder:

$ for i in SET_SYSTEM_SLEEP_PM_OPS SET_LATE_SYSTEM_SLEEP_PM_OPS
SET_NOIRQ_SYSTEM_SLEEP_PM_OPS SET_RUNTIME_PM_OPS SIMPLE_DEV_PM_OPS
UNIVERSAL_DEV_PM_OPS ; do echo `git grep -wl $i | wc  -l` $i ; done

459 SET_SYSTEM_SLEEP_PM_OPS
51 SET_LATE_SYSTEM_SLEEP_PM_OPS
59 SET_NOIRQ_SYSTEM_SLEEP_PM_OPS
497 SET_RUNTIME_PM_OPS
797 SIMPLE_DEV_PM_OPS
20 UNIVERSAL_DEV_PM_OPS

About half of those actually use an #ifdef, while the other half does
not:

$ git grep -wl 'SET_SYSTEM_SLEEP_PM_OPS\|SET_RUNTIME_PM_OPS\|SIMPLE_DEV_PM_OPS\|UNIVERSAL_DEV_PM_OPS'
 | xargs grep -l CONFIG_PM | wc -l
712
$ git grep -wl 'SET_SYSTEM_SLEEP_PM_OPS\|SET_RUNTIME_PM_OPS\|SIMPLE_DEV_PM_OPS\|UNIVERSAL_DEV_PM_OPS'
 | xargs grep -L CONFIG_PM | wc -l
745

If we rename the macros in the first half of this using a script, then we should
be able to change the behavior of the normal macros to use the new pm_ptr().

         Arnd