Re: [PATCH v1 4/8] gpiolib: Get rid of ARCH_NR_GPIOS

[Andy Shevchenko]

On Mon, Aug 29, 2022 at 7:19 PM Christophe Leroy
<christophe.leroy@xxxxxxxxxx> wrote:
>
> Since commit 14e85c0e69d5 ("gpio: remove gpio_descs global array")
> there is no limitation on the number of GPIOs that can be allocated
> in the system since the allocation is fully dynamic.
>
> ARCH_NR_GPIOS is today only used in order to provide downwards
> gpiobase allocation from that value, while static allocation is
> performed upwards from 0. However that has the disadvantage of
> limiting the number of GPIOs that can be registered in the system.
>
> To overcome this limitation without requiring each and every
> platform to provide its 'best-guess' maximum number, rework the
> allocation to allocate upwards, allowing approx 2 millions of
> GPIOs.
>
> In order to still allow static allocation for legacy drivers, define
> GPIO_DYNAMIC_BASE with the value 256 as the start for dynamic
> allocation.

Not sure about 256, but I understand that this can only be the best guess.

-- 
With Best Regards,
Andy Shevchenko