linux-kernel - Re: [PATCH v2 10/10] pinctrl: tegra: Switch to use DEFINE_NOIRQ_DEV_PM

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Date:   Tue, 18 Jul 2023 13:55:05 +0200
From:   Paul Cercueil <paul@...pouillou.net>
To:     Thierry Reding <thierry.reding@...il.com>
Cc:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Balsam CHIHI <bchihi@...libre.com>,
        Claudiu Beznea <claudiu.beznea@...rochip.com>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mediatek@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-renesas-soc@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-pm@...r.kernel.org, Andy Shevchenko <andy@...nel.org>,
        Sean Wang <sean.wang@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        Andrew Lunn <andrew@...n.ch>,
        Gregory Clement <gregory.clement@...tlin.com>,
        Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>,
        Ludovic Desroches <ludovic.desroches@...rochip.com>,
        Nicolas Ferre <nicolas.ferre@...rochip.com>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>
Subject: Re: [PATCH v2 10/10] pinctrl: tegra: Switch to use
 DEFINE_NOIRQ_DEV_PM_OPS() helper

Le mardi 18 juillet 2023 à 13:41 +0200, Thierry Reding a écrit :
> On Tue, Jul 18, 2023 at 10:42:47AM +0200, Paul Cercueil wrote:
> > Hi Thierry,
> > 
> > Le mardi 18 juillet 2023 à 09:45 +0200, Thierry Reding a écrit :
> > > On Mon, Jul 17, 2023 at 09:14:12PM +0200, Paul Cercueil wrote:
> > > > Hi Andy,
> > > > 
> > > > Le lundi 17 juillet 2023 à 20:28 +0300, Andy Shevchenko a
> > > > écrit :
> > > > > Since pm.h provides a helper for system no-IRQ PM callbacks,
> > > > > switch the driver to use it instead of open coded variant.
> > > > > 
> > > > > Signed-off-by: Andy Shevchenko
> > > > > <andriy.shevchenko@...ux.intel.com>
> > > > > ---
> > > > >  drivers/pinctrl/tegra/pinctrl-tegra.c | 5 +----
> > > > >  1 file changed, 1 insertion(+), 4 deletions(-)
> > > > > 
> > > > > diff --git a/drivers/pinctrl/tegra/pinctrl-tegra.c
> > > > > b/drivers/pinctrl/tegra/pinctrl-tegra.c
> > > > > index 4547cf66d03b..734c71ef005b 100644
> > > > > --- a/drivers/pinctrl/tegra/pinctrl-tegra.c
> > > > > +++ b/drivers/pinctrl/tegra/pinctrl-tegra.c
> > > > > @@ -747,10 +747,7 @@ static int tegra_pinctrl_resume(struct
> > > > > device
> > > > > *dev)
> > > > >         return 0;
> > > > >  }
> > > > >  
> > > > > -const struct dev_pm_ops tegra_pinctrl_pm = {
> > > > > -       .suspend_noirq = &tegra_pinctrl_suspend,
> > > > > -       .resume_noirq = &tegra_pinctrl_resume
> > > > > -};
> > > > > +DEFINE_NOIRQ_DEV_PM_OPS(tegra_pinctrl_pm,
> > > > > tegra_pinctrl_suspend,
> > > > > tegra_pinctrl_resume);
> > > > >  
> > > > >  static bool tegra_pinctrl_gpio_node_has_range(struct
> > > > > tegra_pmx
> > > > > *pmx)
> > > > >  {
> > > > 
> > > > Another driver where using EXPORT_GPL_DEV_PM_OPS() would make
> > > > more
> > > > sense.
> > > 
> > > We don't currently export these PM ops because none of the Tegra
> > > pinctrl
> > > drivers can be built as a module.
> > 
> > This doesn't change anything. You'd want to use
> > EXPORT_GPL_DEV_PM_OPS
> > (or better, the namespaced version) so that the PM ops can be
> > defined
> > in one file and referenced in another, while still having them
> > garbage-
> > collected when CONFIG_PM is disabled.
> 
> Looking at the definition of EXPORT_GPL_DEV_PM_OPS(), it will cause
> an
> EXPORT_SYMBOL_GPL() to be added. So there very well is a change. And
> it's a completely bogus change because no module is ever going to use
> that symbol. If we were to ever support building the pinctrl driver
> as
> a module, then this would perhaps make sense, but we don't.

In this particular case the EXPORT_SYMBOL_GPL() isn't really important,
the rest of EXPORT_GPL_DEV_PM_OPS() is.

I don't think having a symbol exported it is a big deal, TBH, if you
use the namespaced version. If you really don't want that, we need a
version of EXPORT_GPL_DEV_PM_OPS() that doesn't export the symbol.

-Paul