linux-kernel - Re: [PATCH v12 3/7] gpiolib: of: make fwnode take precedence in struct gpio

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Message-ID: <CAMRc=MeWfKHWFKwRjaqczrfwhAodpDLgrWKF-zqXCsjd=gMv3g@mail.gmail.com>
Date:   Fri, 3 Dec 2021 20:28:34 +0100
From:   Bartosz Golaszewski <brgl@...ev.pl>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Kent Gibson <warthog618@...il.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Shuah Khan <shuah@...nel.org>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-kselftest@...r.kernel.org
Subject: Re: [PATCH v12 3/7] gpiolib: of: make fwnode take precedence in
 struct gpio_chip

On Fri, Dec 3, 2021 at 8:04 PM Andy Shevchenko
<andriy.shevchenko@...ux.intel.com> wrote:
>
> On Fri, Dec 03, 2021 at 08:56:27PM +0200, Andy Shevchenko wrote:
> > On Fri, Dec 03, 2021 at 08:51:56PM +0200, Andy Shevchenko wrote:
> > > On Fri, Dec 03, 2021 at 02:29:59PM +0100, Bartosz Golaszewski wrote:
> >
> > ...
> >
> > > >   if (gc->parent)
> > > >           gdev->dev.of_node = gc->parent->of_node;
> > > >
> > > > + if (gc->fwnode)
> > > > +         gc->of_node = to_of_node(gc->fwnode);
> > > > +
> > > >   /* If the gpiochip has an assigned OF node this takes precedence */
> > > >   if (gc->of_node)
> > > >           gdev->dev.of_node = gc->of_node;
> > >
> > > Similar should be done in acpi_gpio_dev_init():
> > >
> > >     if (gc->fwnode)
> > >             device_set_node(&gdev->dev, gc->fwnode);
> >
> > Hmm... On the second though this should be rather
> >
> >       if (gc->fwnode)
> >               set_secondary_fwnode(&gdev->dev, gc->fwnode);
> >
> > So the logic will be that:
> >  - if we have parent, set primary fwnode to it
> >  - if we have fwnode, set secondary one to it
> >  - otherwise do nothing
>
> Heck, it's Friday...
>
> If we have parent device for several GPIO devices, this won't work right now
> due to limitations of fwnode regarding to the sturct device.
>
> So, it means we may not have shared primary with different secondary fwnodes.
>
> So, come back to the initial suggestion (overwrite it for now):
>
>         /*
>          * If custom fwnode provided, use it. Currently we may not
>          * handle the case where shared primary node has different
>          * secondary ones. Ideally we have to use
>          * set_secondary_fwnode() here.
>          */
>         if (gc->fwnode)
>                 device_set_node(&gdev->dev, gc->fwnode);
>

Other parts of gpiolib-of depend on the of_node being there.
Converting it to fwnode is a whole other task so for now I suggest we
just convert the fwnode to of_node in struct gpio_chip as per my
patch.

Bart