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Message-ID: <20230921103751.GD3449785@google.com>
Date: Thu, 21 Sep 2023 11:37:51 +0100
From: Lee Jones <lee@...nel.org>
To: Stephen Zhang <starzhangzsd@...il.com>
Cc: linux-kernel@...r.kernel.org, zhangshida@...inos.cn,
k2ci <kernel-bot@...inos.cn>
Subject: Re: [PATCH] mfd: cs42l43: fix defined but not used warnings
On Thu, 21 Sep 2023, Stephen Zhang wrote:
> Lee Jones <lee@...nel.org> 于2023年9月20日周三 17:52写道:
> >
> > On Tue, 05 Sep 2023, zhangshida wrote:
> >
> > > From: Shida Zhang <zhangshida@...inos.cn>
> > >
> > > Warnings were generated during compiling for functions like
> > > cs42l43_*_{resume,suspend}:
> > >
> > > ../drivers/mfd/cs42l43.c:1138:12: error: ‘cs42l43_runtime_resume’ defined but not used [-Werror=unused-function]
> > > 1138 | static int cs42l43_runtime_resume(struct device *dev)
> > > | ^~~~~~~~~~~~~~~~~~~~~~
> > > ../drivers/mfd/cs42l43.c:1124:12: error: ‘cs42l43_runtime_suspend’ defined but not used [-Werror=unused-function]
> > > 1124 | static int cs42l43_runtime_suspend(struct device *dev)
> > > | ^~~~~~~~~~~~~~~~~~~~~~~
> > > ../drivers/mfd/cs42l43.c:1106:12: error: ‘cs42l43_resume’ defined but not used [-Werror=unused-function]
> > > 1106 | static int cs42l43_resume(struct device *dev)
> > > | ^~~~~~~~~~~~~~
> > > ../drivers/mfd/cs42l43.c:1076:12: error: ‘cs42l43_suspend’ defined but not used [-Werror=unused-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@...inos.cn>
> > > Signed-off-by: Shida Zhang <zhangshida@...inos.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 = 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 = 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) = {
> > > 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) = {
> 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 = pm_sleep_ptr(suspend_fn), \
> .resume = pm_sleep_ptr(resume_fn), \
> .freeze = pm_sleep_ptr(suspend_fn), \
> .thaw = pm_sleep_ptr(resume_fn), \
> .poweroff = pm_sleep_ptr(suspend_fn), \
> .restore = pm_sleep_ptr(resume_fn),
> ----
> The technique has already been used by the marcos, but it still
> reports the defined-but-not-used warning.
The MACROS can use #ifery since they are located in header files.
#ifery in C files is to be avoided if at all possible.
> 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...
If you're seeing an error, it should be fixed.
Why is this not an issue anywhere else?
Does the same build complain about all the other drivers too?
--
Lee Jones [李琼斯]
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