linux-kernel - Re: [PATCH v5 02/14] gpio: brcmstb: Use modern PM macros

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Message-ID: <CAOiHx==4NSMNVdW163nE-vYf_FtDjS5aHfj5chPr3n6D2Mt9Nw@mail.gmail.com>
Date: Mon, 24 Nov 2025 16:05:29 +0100
From: Jonas Gorski <jonas.gorski@...il.com>
To: Andy Shevchenko <andriy.shevchenko@...el.com>
Cc: Andy Shevchenko <andy.shevchenko@...il.com>, Jisheng Zhang <jszhang@...nel.org>, 
	Doug Berger <opendmb@...il.com>, Florian Fainelli <florian.fainelli@...adcom.com>, 
	bcm-kernel-feedback-list@...adcom.com, 
	Linus Walleij <linus.walleij@...aro.org>, Bartosz Golaszewski <brgl@...ev.pl>, 
	Hoan Tran <hoan@...amperecomputing.com>, Andy Shevchenko <andy@...nel.org>, 
	Daniel Palmer <daniel@...ngy.jp>, Romain Perier <romain.perier@...il.com>, 
	Grygorii Strashko <grygorii.strashko@...com>, Santosh Shilimkar <ssantosh@...nel.org>, 
	Kevin Hilman <khilman@...nel.org>, Robert Jarzmik <robert.jarzmik@...e.fr>, 
	Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>, Masami Hiramatsu <mhiramat@...nel.org>, 
	Shubhrajyoti Datta <shubhrajyoti.datta@....com>, Srinivas Neeli <srinivas.neeli@....com>, 
	Michal Simek <michal.simek@....com>, linux-gpio@...r.kernel.org, 
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	linux-omap@...r.kernel.org
Subject: Re: [PATCH v5 02/14] gpio: brcmstb: Use modern PM macros

On Mon, Nov 24, 2025 at 3:49 PM Andy Shevchenko
<andriy.shevchenko@...el.com> wrote:
>
> On Mon, Nov 24, 2025 at 03:20:00PM +0100, Jonas Gorski wrote:
> > On Mon, Nov 24, 2025 at 2:52 PM Andy Shevchenko
> > <andy.shevchenko@...il.com> wrote:
> > > On Mon, Nov 24, 2025 at 2:40 PM Jonas Gorski <jonas.gorski@...il.com> wrote:
> > > > On Mon, Nov 24, 2025 at 1:39 AM Jisheng Zhang <jszhang@...nel.org> wrote:
>
> ...
>
> > > > >  static const struct dev_pm_ops brcmstb_gpio_pm_ops = {
> > > > > -       .suspend_noirq  = brcmstb_gpio_suspend,
> > > > > -       .resume_noirq = brcmstb_gpio_resume,
> > > > > +       .suspend_noirq = pm_sleep_ptr(brcmstb_gpio_suspend),
> > > > > +       .resume_noirq = pm_sleep_ptr(brcmstb_gpio_resume),
> > > > >  };
>
> ...
>
> > > > > -               .pm = &brcmstb_gpio_pm_ops,
> > > > > +               .pm = pm_sleep_ptr(&brcmstb_gpio_pm_ops),
> > > >
> > > > won't this cause a "brcmstb_gpio_pm_ops is unused" compile warning for
> > > > !CONFIG_PM_SLEEP?
> > > >
> > > > You probably need to add a __maybe_unused to brcmstb_gpio_pm_ops
> > > > (which incidentally DEFINE_NOIRQ_DEV_PM_OPS() also doesn't set, but
> > > > all other *_DEV_PM_OPS() macros do).
>
> Do they? I mean the modern ones and not that are deprecated.
>
> > > Shouldn't it be covered by the same trick as pm_sleep_ptr() does for functions?
> >
> > pm_sleep_ptr() becomes NULL for !CONFIG_PM_SLEEP, so there is no
> > reference then anymore to brcmstb_gpio_pm_ops. You would need a
> > wrapper for brcmstb_gpio_pm_ops itself to conditionally define it to
> > avoid the warning, or add __maybe_unused to it to silence it.
>
> PTR_IF() magic is exactly to make sure compiler will have a visibility while
> dropping a dead code. Did I miss anything?

No, I just was working with old assumptions, so my bad. I faintly
remember that they used to work that way, but maybe I also
misremember. TIL. So disregard my comment.

> > Note how SIMPLE_DEV_PM_OPS() and UNIVERSAL_DEV_PM_OPS() tag the struct
> > with it (for that reason I assume).
>
> Both are deprecated. Not a good orienteer.
> None of the new approach uses __maybe_unused. (See DEFINE_*() macros in pm.h.)

Maybe that some were using it was confusing me into thinking it is required.

Best regards,
Jonas