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References: <20230905021209.1412987-1-zhangshida@kylinos.cn> <20230920095248.GC13143@google.com>
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From:   Stephen Zhang <starzhangzsd@gmail.com>
Date:   Thu, 21 Sep 2023 10:46:52 +0800
Message-ID: <CANubcdVuiBciEQu14hOUvgSYo2+1okQ4ed-tJJa5Xo_3jieGzg@mail.gmail.com>
Subject: Re: [PATCH] mfd: cs42l43: fix defined but not used warnings
To:     Lee Jones <lee@kernel.org>
Cc:     linux-kernel@vger.kernel.org, zhangshida@kylinos.cn,
        k2ci <kernel-bot@kylinos.cn>
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Lee Jones <lee@kernel.org> =E4=BA=8E2023=E5=B9=B49=E6=9C=8820=E6=97=A5=E5=
=91=A8=E4=B8=89 17:52=E5=86=99=E9=81=93=EF=BC=9A
>
> On Tue, 05 Sep 2023, zhangshida wrote:
>
> > From: Shida Zhang <zhangshida@kylinos.cn>
> >
> > Warnings were generated during compiling for functions like
> > cs42l43_*_{resume,suspend}:
> >
> > ../drivers/mfd/cs42l43.c:1138:12: error: =E2=80=98cs42l43_runtime_resum=
e=E2=80=99 defined but not used [-Werror=3Dunused-function]
> >  1138 | static int cs42l43_runtime_resume(struct device *dev)
> >       |            ^~~~~~~~~~~~~~~~~~~~~~
> > ../drivers/mfd/cs42l43.c:1124:12: error: =E2=80=98cs42l43_runtime_suspe=
nd=E2=80=99 defined but not used [-Werror=3Dunused-function]
> >  1124 | static int cs42l43_runtime_suspend(struct device *dev)
> >       |            ^~~~~~~~~~~~~~~~~~~~~~~
> > ../drivers/mfd/cs42l43.c:1106:12: error: =E2=80=98cs42l43_resume=E2=80=
=99 defined but not used [-Werror=3Dunused-function]
> >  1106 | static int cs42l43_resume(struct device *dev)
> >       |            ^~~~~~~~~~~~~~
> > ../drivers/mfd/cs42l43.c:1076:12: error: =E2=80=98cs42l43_suspend=E2=80=
=99 defined but not used [-Werror=3Dunused-function]
> >  1076 | static int cs42l43_suspend(struct device *dev)
> >
> > Fix it by guarding it with CONFIG_PM/CONFIG_PM_SLEEP.
> >
> > Reported-by: k2ci <kernel-bot@kylinos.cn>
> > Signed-off-by: Shida Zhang <zhangshida@kylinos.cn>
> > ---
> >  drivers/mfd/cs42l43.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> >
> > diff --git a/drivers/mfd/cs42l43.c b/drivers/mfd/cs42l43.c
> > index 37b23e9bae82..e589a61c118d 100644
> > --- a/drivers/mfd/cs42l43.c
> > +++ b/drivers/mfd/cs42l43.c
> > @@ -1073,6 +1073,7 @@ void cs42l43_dev_remove(struct cs42l43 *cs42l43)
> >  }
> >  EXPORT_SYMBOL_NS_GPL(cs42l43_dev_remove, MFD_CS42L43);
> >
> > +#ifdef CONFIG_PM_SLEEP
> >  static int cs42l43_suspend(struct device *dev)
> >  {
> >       struct cs42l43 *cs42l43 =3D dev_get_drvdata(dev);
> > @@ -1120,7 +1121,9 @@ static int cs42l43_resume(struct device *dev)
> >
> >       return 0;
> >  }
> > +#endif
> >
> > +#ifdef CONFIG_PM
> >  static int cs42l43_runtime_suspend(struct device *dev)
> >  {
> >       struct cs42l43 *cs42l43 =3D dev_get_drvdata(dev);
> > @@ -1176,6 +1179,7 @@ static int cs42l43_runtime_resume(struct device *=
dev)
> >
> >       return ret;
> >  }
> > +#endif
> >
> >  EXPORT_NS_GPL_DEV_PM_OPS(cs42l43_pm_ops, MFD_CS42L43) =3D {
> >       SET_SYSTEM_SLEEP_PM_OPS(cs42l43_suspend, cs42l43_resume)
>
> I see a bunch of drivers using PM helpers and not many of them are
> are being guarded by ugly #ifery.  Please find out what they're doing to
> solve the same issue and replicate that instead.
>
> Here's a really big hint:
>
>   `git log --oneline 02313a90095fb`
>

Thanks, I've learned something from the hint.

And I also checked the code:
-----
EXPORT_NS_GPL_DEV_PM_OPS(cs42l43_pm_ops, MFD_CS42L43) =3D {
        SET_SYSTEM_SLEEP_PM_OPS(cs42l43_suspend, cs42l43_resume)
        SET_RUNTIME_PM_OPS(cs42l43_runtime_suspend,
cs42l43_runtime_resume, NULL)
};
----
#ifdef CONFIG_PM_SLEEP
#define SET_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \
        SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn)
#else
#define SET_SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn)
#endif
----
#define SYSTEM_SLEEP_PM_OPS(suspend_fn, resume_fn) \
        .suspend =3D pm_sleep_ptr(suspend_fn), \
        .resume =3D pm_sleep_ptr(resume_fn), \
        .freeze =3D pm_sleep_ptr(suspend_fn), \
        .thaw =3D pm_sleep_ptr(resume_fn), \
        .poweroff =3D pm_sleep_ptr(suspend_fn), \
        .restore =3D pm_sleep_ptr(resume_fn),
----
The technique has already been used by the marcos, but it still
reports the defined-but-not-used warning.
Maybe some compilers still choose to compile these functions in...
Anyway, I will just leave it alone since it is really not a big problem...

Thanks,
Shida


> --
> Lee Jones [=E6=9D=8E=E7=90=BC=E6=96=AF]