Re: [PATCH] gpio: Revert regression in sysfs-gpio (gpiolib.c)

From: Marcelo Roberto Jimenez <marcelo.jimenez@gmail.com>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Bartosz Golaszewski <brgl@bgdev.pl>,
	Thorsten Leemhuis <regressions@leemhuis.info>,
	stable <stable@vger.kernel.org>,
	regressions@lists.linux.dev,
	Linus Walleij <linus.walleij@linaro.org>,
	"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
	Thierry Reding <treding@nvidia.com>,
	Vidya Sagar <vidyas@nvidia.com>,
	Stephen Rothwell <sfr@canb.auug.org.au>,
	Edmond Chung <edmondchung@google.com>,
	Andrew Chant <achant@google.com>,
	Will McVicker <willmcvicker@google.com>,
	Sergio Tanzilli <tanzilli@acmesystems.it>
Subject: Re: [PATCH] gpio: Revert regression in sysfs-gpio (gpiolib.c)
Date: Mon, 20 Dec 2021 17:41:34 -0300	[thread overview]
Message-ID: <CACjc_5qaGFiuTyEHt5sy_EkCBd6bGgQp-T19GyATQw=jeoLGpg@mail.gmail.com> (raw)
In-Reply-To: <CAMuHMdVp621B0DywkW6sx6wNcPFez9=3-=cfSo7UoRttJ6QXCg@mail.gmail.com>

Hi Geert,

On Mon, Dec 20, 2021 at 12:14 PM Geert Uytterhoeven
<geert@linux-m68k.org> wrote:
>
> On Mon, Dec 20, 2021 at 3:57 PM Bartosz Golaszewski <brgl@bgdev.pl> wrote:
> > On Sat, Dec 18, 2021 at 7:28 AM Thorsten Leemhuis
> > <regressions@leemhuis.info> wrote:
> > > [TLDR: I'm adding this regression to regzbot, the Linux kernel
> > > regression tracking bot; most text you find below is compiled from a few
> > > templates paragraphs some of you might have seen already.]
> > >
> > > On 17.12.21 16:35, Marcelo Roberto Jimenez wrote:
> > > > Some GPIO lines have stopped working after the patch
> > > > commit 2ab73c6d8323f ("gpio: Support GPIO controllers without pin-ranges")
> > > >
> > > > And this has supposedly been fixed in the following patches
> > > > commit 89ad556b7f96a ("gpio: Avoid using pin ranges with !PINCTRL")
> > > > commit 6dbbf84603961 ("gpiolib: Don't free if pin ranges are not defined")
> > >
> > > There seems to be a backstory here. Are there any entries and bug
> > > trackers or earlier discussions everyone that looks into this should be
> > > aware of?
> > >
> >
> > Agreed with Thorsten. I'd like to first try to determine what's wrong
> > before reverting those, as they are correct in theory but maybe the
> > implementation missed something.
> >
> > Have you tried tracing the execution on your platform in order to see
> > what the driver is doing?
>
> Looking at commits that have related Fixes tags:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=bf781869e5cf3e4ec1a47dad69b6f0df97629cbd
> https://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl.git/commit/?id=e8f24c58d1b69ecf410a673c22f546dc732bb879
>

Interesting. These seem to imply that gpiolib-sysfs.c should be
allocating a pinctrl list. That seems very easy to do in the DTD,
although I don't really know if that is the right thing to do. Doing
it in the code seems more appropriate, what do you think?

> Gr{oetje,eeting}s,
>
>                         Geert

Regards,
Marcelo.