linux-kernel - Re: [rft, PATCH v3 1/1] gpiolib: Get rid of not used of

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Message-ID: <Y3TvKJAejVAZEVPJ@smile.fi.intel.com>
Date:   Wed, 16 Nov 2022 16:09:44 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Thierry Reding <treding@...dia.com>
Cc:     Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Bartosz Golaszewski <bartosz.golaszewski@...aro.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        linux-gpio@...r.kernel.org, linux-acpi@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Bartosz Golaszewski <brgl@...ev.pl>
Subject: Re: [rft, PATCH v3 1/1] gpiolib: Get rid of not used of_node member

On Wed, Nov 16, 2022 at 02:47:07PM +0100, Thierry Reding wrote:
> On Wed, Nov 16, 2022 at 11:18:59AM +0200, Andy Shevchenko wrote:
> > All new drivers should use fwnode and / or parent to provide the
> > necessary information to the GPIO library.

...

> > +	/* If the calling driver did not initialize firmware node, do it here */
> >  	if (gc->fwnode)
> >  		fwnode = gc->fwnode;
> >  	else if (gc->parent)
> >  		fwnode = dev_fwnode(gc->parent);
> > +	gc->fwnode = fwnode;
> 
> I'm not sure we want to set this one. We recently discussed this in
> another thread and my reading is that gc->fwnode is supposed to be used
> only to explicitly override which fwnode to use if the default isn't
> appropriate. Right now the standard way to access the device's fwnode
> seems to be dev_fwnode(&gdev->dev), with only very few exceptions, so
> it'd be great if we could settle on that, rather than introduce a second
> field that contains the same value and use them interchangeably.
> 
> One way we could enforce this is by setting gc->fwnode to NULL here
> instead of fwnode. That should cause a crash anywhere it's used after
> this, so we should be able to easily weed out any abuses.
> 
> Of course if people prefer to use gc->fwnode instead, then we may want
> to remove all uses of gdev->dev.fwnode. There's simply no point in
> keeping the same value in two different place, it's just going to lead
> to a big mess.

I prefer that we explicitly use GPIO device firmware node.
Independently on this message I came up with another patch
(I'm just about to sent it right away) which I think it
the best to have in current case.

Ideally I would like to see const struct gpio_chip *gc to be a parameter
to the GPIO chip add(). But it may happen in distant future.

-- 
With Best Regards,
Andy Shevchenko