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From:   Andy Shevchenko <andy.shevchenko@gmail.com>
Date:   Wed, 11 Oct 2023 18:23:02 +0300
Message-ID: <CAHp75Vc2vGEYmbaurzEoh-ejkvFwGeo98LtAGvEq5idXNPgnRQ@mail.gmail.com>
Subject: Re: [PATCH 2/3] gpiolib: provide gpiod_to_gpio_device()
To:     Bartosz Golaszewski <brgl@bgdev.pl>
Cc:     Linus Walleij <linus.walleij@linaro.org>,
        Andy Shevchenko <andy@kernel.org>,
        Peter Korsgaard <peter.korsgaard@barco.com>,
        Peter Rosin <peda@axentia.se>, linux-gpio@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-i2c@vger.kernel.org,
        Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
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On Wed, Oct 11, 2023 at 4:02=E2=80=AFPM Bartosz Golaszewski <brgl@bgdev.pl>=
 wrote:
>
> From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
>
> Accessing struct gpio_chip backing a GPIO device is only allowed for the
> actual providers of that chip.
>
> Similarly to how we introduced gpio_device_find() in order to replace
> the abused gpiochip_find(), let's introduce a counterpart to
> gpiod_to_chip() that returns a reference to the GPIO device owning the
> descriptor. This is done in order to later remove gpiod_to_chip()
> entirely.

My concern with this API is the following scenario:
1. One driver requests the GPIO descriptor.
2. Another driver does take an arbitrary number, converts to a
descriptor and calls for this API.

Is there any (potential) problem?

--=20
With Best Regards,
Andy Shevchenko