linux-kernel - Re: [PATCH] gpiolib: enable CONFIG_GPIOLIB

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Message-Id: <f0a2a000-381e-40d8-a9ac-4d75dba332e9@app.fastmail.com>
Date: Tue, 29 Jul 2025 13:57:45 +0200
From: "Arnd Bergmann" <arnd@...db.de>
To: "Geert Uytterhoeven" <geert@...ux-m68k.org>,
 "Arnd Bergmann" <arnd@...nel.org>
Cc: "Linus Walleij" <linus.walleij@...aro.org>,
 "Bartosz Golaszewski" <brgl@...ev.pl>,
 "Alexander Sverdlin" <alexander.sverdlin@...il.com>,
 "kernel test robot" <lkp@...el.com>, "Peng Fan" <peng.fan@....com>,
 "Koichiro Den" <koichiro.den@...onical.com>, "Lee Jones" <lee@...nel.org>,
 "Geert Uytterhoeven" <geert+renesas@...der.be>,
 André Draszik <andre.draszik@...aro.org>,
 "Niko Pasaloukos" <nikolaos.pasaloukos@...ize.com>,
 "Thomas Richard" <thomas.richard@...tlin.com>, "Yixun Lan" <dlan@...too.org>,
 "Lars-Peter Clausen" <lars@...afoo.de>,
 "Andy Shevchenko" <andriy.shevchenko@...ux.intel.com>,
 "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] gpiolib: enable CONFIG_GPIOLIB_LEGACY even for !GPIOLIB

On Tue, Jul 29, 2025, at 12:47, Geert Uytterhoeven wrote:
>>
>> -if GPIOLIB
>> -
>>  config GPIOLIB_LEGACY
>>         def_bool y
>>
>> +if GPIOLIB
>> +
>>  config GPIOLIB_FASTPATH_LIMIT
>>         int "Maximum number of GPIOs for fast path"
>>         range 32 512
>
> This won't work for everything.
> While I now get CONFIG_GPIOLIB_LEGACY=y in all m68k defconfigs, and
> simple inline functions like gpio_is_valid() are now available, more
> complex functions will still fail, as drivers/gpio/gpiolib-legacy.c
> is not built.
>
> drivers/Makefile:
>
>     obj-$(CONFIG_GPIOLIB)           += gpio/
>

Hi Geert,

Do you have an example config that shows this problem? 
I've tried a couple of configurations on m68k now but are unable
to reproduce this, using 'defconfig' (without GPIOLIB) and
'm5475evb_defconfig' (with GPIOLIB).

The intention of this patch (in combination with the previous one)
was that the legacy interfaces would still behave exactly like
before, falling back to the stubs when GPIOLIB is disabled.

    Arnd