linux-kernel - Re: [PATCH v3 04/11] gpiolib: provide gpio_device_find_by

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Date:   Wed, 27 Sep 2023 14:42:28 +0200
From:   Bartosz Golaszewski <brgl@...ev.pl>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-acpi@...r.kernel.org,
        Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH v3 04/11] gpiolib: provide gpio_device_find_by_label()

On Wed, Sep 27, 2023 at 2:33 PM Andy Shevchenko
<andriy.shevchenko@...ux.intel.com> wrote:
>
> On Wed, Sep 27, 2023 at 01:22:36PM +0200, Bartosz Golaszewski wrote:
> > On Mon, Sep 18, 2023 at 9:19 AM Andy Shevchenko
> > <andriy.shevchenko@...ux.intel.com> wrote:
> > >
> > > On Fri, Sep 15, 2023 at 05:03:19PM +0200, Bartosz Golaszewski wrote:
> > > > From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> > > >
> > > > By far the most common way of looking up GPIO devices is using their
> > > > label. Provide a helpers for that to avoid every user implementing their
> > > > own matching function.
>
> ...
>
> > > > +static int gpio_chip_match_by_label(struct gpio_chip *gc, void *label)
> > > > +{
> > > > +     return gc->label && !strcmp(gc->label, label);
> > > > +}
> > >
> > > I am still wondering if we can oblige providers to have label to be non-empty.
> >
> > Of course we can. Just bail out of gpiochip_add_data_with_key() if it
> > is. But that's material for a different patch.
>
> Yes, but my point here is that
> 1) the current users are already following this requirement;
> 2) the enforcement can be done explicitly somewhere (in the register function).
>
> Is the 1) incorrect assumption?
>

I remember doing a quick glance over GPIO providers and it looks like
ALL of them set the label. But I may have missed something. I would
start with a warning.

Bart