linux-kernel - Re: [PATCH 1/4] gpiolib: add opt-out for existing drivers with static GPIO base

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Message-ID: <CAHp75VcnB37ET8mW=m5sXwP4qDQDUPKL0yRy8n49m++zShqPMA@mail.gmail.com>
Date: Tue, 14 Jan 2025 11:49:12 +0200
From: Andy Shevchenko <andy.shevchenko@...il.com>
To: Ahmad Fatoum <a.fatoum@...gutronix.de>
Cc: Linus Walleij <linus.walleij@...aro.org>, Bartosz Golaszewski <brgl@...ev.pl>, 
	Andy Whitcroft <apw@...onical.com>, Joe Perches <joe@...ches.com>, 
	Dwaipayan Ray <dwaipayanray1@...il.com>, Lukas Bulwahn <lukas.bulwahn@...il.com>, 
	Fabio Estevam <festevam@...il.com>, Shawn Guo <shawnguo@...nel.org>, 
	Sascha Hauer <s.hauer@...gutronix.de>, Pengutronix Kernel Team <kernel@...gutronix.de>, 
	Dario Binacchi <dario.binacchi@...rulasolutions.com>, Haibo Chen <haibo.chen@....com>, 
	Catalin Popescu <catalin.popescu@...ca-geosystems.com>, linux-gpio@...r.kernel.org, 
	linux-kernel@...r.kernel.org, imx@...ts.linux.dev, 
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 1/4] gpiolib: add opt-out for existing drivers with static
 GPIO base

On Tue, Jan 14, 2025 at 12:20 AM Ahmad Fatoum <a.fatoum@...gutronix.de> wrote:
>
> Some drivers have had deterministic GPIO numbering for most of
> their existence, e.g. the i.MX GPIO since commit 7e6086d9e54a
> ("gpio/mxc: specify gpio base for device tree probe"), more than
> 12 years ago.
>
> Reverting this to dynamically numbered will break existing setups in
> the worst manner possible: The build will succeed, the kernel will not
> print warnings, but users will find their devices essentially toggling
> GPIOs at random with the potential of permanent damage.
>
> As these concerns won't go away until the sysfs interface is removed,
> let's add a new struct gpio_chip::legacy_static_base member that can be
> used by existing drivers that have been grandfathered in to suppress
> the warning currently being printed:
>
>   gpio gpiochip0: Static allocation of GPIO base is deprecated,
>   use dynamic allocation.

Warning is harmless and still a good reminder for the stuff that needs
more love.
NAK.

-- 
With Best Regards,
Andy Shevchenko