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From: Andy Shevchenko <andy.shevchenko@gmail.com>
Date: Wed, 10 Jan 2024 13:10:51 +0200
Message-ID: <CAHp75Vc8UN2kyxGtV0tCF+xcRLAxg0qijTvHWXXtdTA9nY-h3w@mail.gmail.com>
Subject: Re: [PATCH 0/7] Documentation: gpio: add character device userspace
 API documentation
To: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Kent Gibson <warthog618@gmail.com>, linux-kernel@vger.kernel.org, 
	linux-gpio@vger.kernel.org, linux-doc@vger.kernel.org, brgl@bgdev.pl, 
	linus.walleij@linaro.org, andy@kernel.org, corbet@lwn.net
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On Wed, Jan 10, 2024 at 10:16=E2=80=AFAM Vegard Nossum <vegard.nossum@oracl=
e.com> wrote:
> On 10/01/2024 00:45, Kent Gibson wrote:
> > On Tue, Jan 09, 2024 at 10:00:26PM +0200, Andy Shevchenko wrote:
> >> On Tue, Jan 9, 2024 at 4:00=E2=80=AFPM Kent Gibson <warthog618@gmail.c=
om> wrote:
> >>
> >> May we actually state in the documentation that sysfs is subject to
> >> remove at some point?
> >
> > So formally define what "deprecated" means?
> > Is that covered in the higher level documentation somewhere?
> > If so I'm more than happy to provide a reference.
>
> We have a few files that may be relevant here, that I'm aware of:
>
> 1) https://docs.kernel.org/admin-guide/sysfs-rules.html
>
> documents some general assumptions that userspace can make about the
> stability of sysfs and its files
>
> 2) https://docs.kernel.org/admin-guide/abi.html
>
> This is the public-facing, somewhat machine-readable repository of what
> is supposed to be the kernel's ABI/API, including "obsolete" and
> "removed" interfaces.
>
> 3) Documentation/ABI/README
>
> describes the process of deprecating an interface

Yes and GPIO currently is under obsolete section with also this:

"This ABI is deprecated and will be removed after 2020. It is replaced
with the GPIO character device."

https://docs.kernel.org/admin-guide/abi-obsolete.html#symbols-under-sys-cla=
ss

So, proposed cleanup series should probably rely on this documentation
among other existing descriptions of sysfs GPIO.

--=20
With Best Regards,
Andy Shevchenko