linux-kernel - Re: [PATCH v2 4/9] gpio: sysfs: don't use driver data in sysfs callbacks for line attributes

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Message-ID: <aF67oAqLmRJzy4Zt@black.fi.intel.com>
Date: Fri, 27 Jun 2025 18:41:20 +0300
From: Andy Shevchenko <andriy.shevchenko@...el.com>
To: Bartosz Golaszewski <brgl@...ev.pl>
Cc: Ahmad Fatoum <a.fatoum@...gutronix.de>,
	Kent Gibson <warthog618@...il.com>,
	Jan Lübbe <jlu@...gutronix.de>,
	Marek Vasut <marex@...x.de>,
	Geert Uytterhoeven <geert+renesas@...der.be>,
	Linus Walleij <linus.walleij@...aro.org>,
	linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
	Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH v2 4/9] gpio: sysfs: don't use driver data in sysfs
 callbacks for line attributes

On Mon, Jun 23, 2025 at 10:59:52AM +0200, Bartosz Golaszewski wrote:
> 
> Currently each exported GPIO is represented in sysfs as a separate class
> device. This allows us to simply use dev_get_drvdata() to retrieve the
> pointer passed to device_create_with_groups() from sysfs ops callbacks.
> 
> However, we're preparing to add a parallel set of per-line sysfs
> attributes that will live inside the associated gpiochip group. They are
> not registered as class devices and so have the parent device passed as
> argument to their callbacks (the GPIO chip class device).
> 
> Put the attribute structs inside the GPIO descriptor data and
> dereference the relevant ones using container_of() in the callbacks.
> This way, we'll be able to reuse the same code for both the legacy and
> new GPIO attributes.

...

> -	struct gpiod_data *data = dev_get_drvdata(dev);
> +	struct gpiod_data *data = container_of(attr, struct gpiod_data,
> +					       dir_attr);

Defining once something like

#define to_gpiod_data() ...

we may leave this and others as one-liners.

...

> +	attrs[GPIO_SYSFS_LINE_ATTR_ACTIVE_LOW] =
> +						&data->active_low_attr.attr;

What's the point of two lines here?

-- 
With Best Regards,
Andy Shevchenko