linux-kernel - Re: [PATCH v3 04/10] gpio: aggregator: refactor the code to add GPIO desc in the forwarder

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Message-ID: <aAE3gRH08WuuIFai@smile.fi.intel.com>
Date: Thu, 17 Apr 2025 20:16:49 +0300
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Thomas Richard <thomas.richard@...tlin.com>
Cc: Linus Walleij <linus.walleij@...aro.org>,
	Bartosz Golaszewski <brgl@...ev.pl>,
	Geert Uytterhoeven <geert+renesas@...der.be>,
	linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
	thomas.petazzoni@...tlin.com, DanieleCleri@...on.eu,
	GaryWang@...on.com.tw
Subject: Re: [PATCH v3 04/10] gpio: aggregator: refactor the code to add GPIO
 desc in the forwarder

On Wed, Apr 16, 2025 at 04:08:12PM +0200, Thomas Richard wrote:
> Create a dedicated function to add a GPIO desc in the forwarder. Instead of
> passing an array of GPIO desc, now the GPIO desc are passed on by one to
> the forwarder.

...

> +static int gpiochip_fwd_add_gpio_desc(struct gpiochip_fwd *fwd,
> +				      struct gpio_desc *desc,
> +				      unsigned int offset)
> +{
> +	struct gpio_chip *parent = gpiod_to_chip(desc);
> +	struct gpio_chip *chip = &fwd->chip;
> +
> +	if (offset > chip->ngpio)

>= ?

> +		return -EINVAL;

> +	if (fwd->descs[offset])
> +		return -EEXIST;

Not sure we need this. I would rather think that something inside struct
gpiochip_fwd should track this. OTOH, I understand that you want to have
sparse lists perhaps. I;m wondering why GPIO valid mask can't be used for
this purposes?

> +	/*
> +	 * If any of the GPIO lines are sleeping, then the entire forwarder
> +	 * will be sleeping.
> +	 * If any of the chips support .set_config(), then the forwarder will
> +	 * support setting configs.
> +	 */
> +	if (gpiod_cansleep(desc))
> +		chip->can_sleep = true;
> +
> +	if (parent && parent->set_config)
> +		chip->set_config = gpio_fwd_set_config;
> +
> +	fwd->descs[offset] = desc;
> +
> +	dev_dbg(chip->parent, "%u => gpio %d irq %d\n", offset,
> +		desc_to_gpio(desc), gpiod_to_irq(desc));
> +
> +	return 0;
> +}

The bottom line is that I'm fine with this change without additional checks,
add them when function will be used not only in the original loop.

-- 
With Best Regards,
Andy Shevchenko