Re: [RFC PATCH] pinctrl: sunxi: convert to GPIO_GENERIC

[Bartosz Golaszewski]

On Sun, 15 Mar 2026 01:42:05 +0100, Andre Przywara
<andre.przywara@xxxxxxx> said:
> On Sat, 14 Mar 2026 13:14:25 +0800
> Icenowy Zheng <uwu@xxxxxxxxxx> wrote:
>
>> 在 2026-03-13五的 01:06 +0100，Andre Przywara写道：
>> > Allwinner SoCs combine pinmuxing and GPIO control in one device/MMIO
>> > register frame. So far we were instantiating one GPIO chip per
>> > pinctrl
>> > device, which covers multiple banks of up to 32 GPIO pins per bank.
>> > The
>> > GPIO numbers were set to match the absolute pin numbers, even across
>> > the
>> > typically two instances of the pinctrl device.
>> >
>> > Convert the GPIO part of the sunxi pinctrl over to use the
>> > gpio_generic
>> > framework. This alone allows to remove some sunxi specific code,
>> > which
>> > is replaced with the existing generic code. This will become even
>> > more
>> > useful with the upcoming A733 support, which adds set and clear
>> > registers for the output.
>> > As a side effect this also changes the GPIO device and number
>> > allocation: Each bank is now represented by its own gpio_chip, with
>> > only
>> > as many pins as there are actually implemented. The numbering is left
>> > up
>>
>> Ah, is this a userspace API break?
>
> Was that ever a guaranteed user space API? Or just something
> that everyone relied on because it was always the same (until it
> wasn't)? Similar to /dev/mmcblk0 being the SD card?
> And ignoring the ill-fated old-style sysfs interface for now, how does
> this work with libgpiod? Would it still use the absolute pin numbers?
>
> I mean looking at that warning about the forced GPIO numbering we
> get, using base = -1 seems to be the recommended way?
>

My view is this: for libgpiod, there are no absolute GPIO numbers and the
ordering of GPIO chip character devices is not guaranteed.

For sysfs: userspace may rightfully expect the global numbering to stay the
same. I don't like it but this is the kernel policy.

Here however, there's another thing: the fact that a single GPIO chips is now
split into several. I don't mind it but if someone complains, it would have
to be reverted.

Bartosz