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

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Message-ID: <97baffcd-35cc-49a0-95e9-d1ceac966dc3@pengutronix.de>
Date: Tue, 14 Jan 2025 11:06:53 +0100
From: Ahmad Fatoum <a.fatoum@...gutronix.de>
To: Andy Shevchenko <andy.shevchenko@...il.com>
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 14.01.25 10:49, Andy Shevchenko wrote:
> 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.

A warning is a call-to-action and it's counterproductive to keep tricking
people into removing the static base and breaking other users' scripts.

I don't understand what love you think this will spawn with regards
to the i.MX GPIO driver. Can you explain?

Cheers,
Ahmad

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