Re: [PATCH 6/6] [v5] gpiolib: turn off legacy interface by default

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [High] Drivers depending on `GPIOLIB_LEGACY` rather than selecting it are rendered unselectable and silently disabled on normal builds.
- [Low] Disabling CONFIG_GPIOLIB_LEGACY by default causes widespread build failures for platforms and drivers still relying on legacy GPIO functions.
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commit bad1a2df68babe59200c7570528e8b8606464b68
Author: Arnd Bergmann <arnd@arndb.de>

gpiolib: turn off legacy interface by default

This commit changes the GPIOLIB_LEGACY configuration to default to 'n' instead
of 'y'. It restricts manual selection to builds where COMPILE_TEST is enabled,
intending to only build the legacy interface on platforms that require it.

> All users of the legacy interface now select CONFIG_GPIOLIB_LEGACY,
> so it can be turned off by default and only get built on platforms
> that still have one unconverted driver.

[Severity: High]
Is this description entirely accurate?

There appear to be drivers that use 'depends on GPIOLIB_LEGACY' rather than
selecting it, such as MFD_AAT2870_CORE, MFD_SI476X_CORE, and
SND_SOC_TLV320DAC33.

If GPIOLIB_LEGACY defaults to 'n' without COMPILE_TEST enabled, will these
drivers be rendered unselectable and silently disabled on normal builds?

> diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
> index 020e51e30317a..543de15a12f63 100644
> --- a/drivers/gpio/Kconfig
> +++ b/drivers/gpio/Kconfig
> @@ -4,7 +4,14 @@
>  #
>  
>  config GPIOLIB_LEGACY
> -	def_bool y
> +	bool "Legacy GPIO interfaces" if COMPILE_TEST

[Severity: Low]
Could disabling this by default cause build failures on legacy platforms that
still call GPIO functions but do not explicitly select GPIOLIB_LEGACY?

For instance, arch/arm/mach-pxa/am200epd.c still uses gpio_request():

arch/arm/mach-pxa/am200epd.c:am200_init_gpio_regs() {
        ...
        err = gpio_request(gpios[i], gpio_names[i]);
        ...
}

Because include/linux/gpio.h excludes the legacy prototypes when
CONFIG_GPIOLIB_LEGACY is disabled, will this cause implicit declaration
compiler errors during standard builds for architectures like PXA?

> +	help
> +	  There are a few legacy platforms that use the traditional GPIO
> +	  number based interfaces instead of GPIO descriptors.
> +	  Say Y here to enable build testing drivers that are specific
> +	  to those platforms.
> +
> +	  If unsure, say N.

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Sashiko AI review · https://sashiko.dev/#/patchset/20260629130329.1291953-1-arnd@kernel.org?part=6