Re: [PATCH] mmc: mediatek: mark PM functions as __maybe_unused

[Paul Cercueil]

Hi,

Le ven. 4 déc. 2020 à 15:14, Arnd Bergmann <arnd@xxxxxxxxxx> a écrit 
:
> On Fri, Dec 4, 2020 at 11:02 AM Ulf Hansson <ulf.hansson@xxxxxxxxxx> 
> wrote:
> >  On Thu, 3 Dec 2020 at 23:29, Arnd Bergmann <arnd@xxxxxxxxxx> wrote:
>
> >  > -#ifdef CONFIG_PM
> >  >  static void msdc_save_reg(struct msdc_host *host)
> >
> >  Shouldn't msdc_save|restore_reg() be turned into "__maybe_unused" 
> > as well?
>
> There is no need since the compiler can figure that out already when 
> there
> is a reference to the function from dead code.
>
> >  >
> >  > -static int msdc_resume(struct device *dev)
> >  > +static int __maybe_unused msdc_resume(struct device *dev)
> >  >  {
> >  >         return pm_runtime_force_resume(dev);
> >  >  }
> >  > -#endif
> >  >
> >  >  static const struct dev_pm_ops msdc_dev_pm_ops = {
> >
> >  You may also change this to a __maybe_unused, as long as you also
> >  assign the .pm pointer in the mt_msdc_driver with
> >  pm_ptr(&msdc_dev_pm_ops).
> >
> >  Ideally the compiler should drop these functions/datas entirely 
> > then.
>
> I don't see a lot of other instances of that yet, and it's fairly new.
> Maybe we should fix it before it gets propagated further.
>
> I would suggest we redefine pm_ptr like
>
> #define pm_ptr(_ptr) (IS_ENABLED(CONFIG_PM) ? (_ptr) : NULL)
>
> and remove the __maybe_unused annotations on those that we
> already have. This also has the effect of dropping the unused
> data from the object, but without having to an an #ifdef or
> __maybe_unused.
>
> Adding Paul and Rafael to Cc for clarification on this.

I didn't think about that. That's smarter and much more elegant.

Cheers,
-Paul