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From: Marcelo Roberto Jimenez <marcelo.jimenez@gmail.com>
To: Thorsten Leemhuis <regressions@leemhuis.info>
Cc: Bartosz Golaszewski <brgl@bgdev.pl>,
	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>,
	Geert Uytterhoeven <geert@linux-m68k.org>,
	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: Tue, 11 Jan 2022 21:09:15 -0300	[thread overview]
Message-ID: <CACjc_5o4n9CNXoER5Va6u0fQhuE9osnUSUwSbHPx0K1yiPUj8g@mail.gmail.com> (raw)
In-Reply-To: <37d074c7-b264-acac-4bf6-65caa4dbab1a@leemhuis.info>

Hi,

On Mon, Jan 10, 2022 at 4:02 AM Thorsten Leemhuis
<regressions@leemhuis.info> wrote:
>
> Hi, this is your Linux kernel regression tracker speaking.
>
> On 20.12.21 21:41, Marcelo Roberto Jimenez wrote:
> > On Mon, Dec 20, 2021 at 11:57 AM 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?
> >
> > Yes. The problem is that there is no list defined for the sysfs-gpio
> > interface. The driver will not perform pinctrl_gpio_request() and will
> > return zero (failure).
> >
> > I don't know if this is the case to add something to a global DTD or
> > to fix it in the sysfs-gpio code.
>
> Out of interest, has any progress been made on this front?
>
> BTW, there was a last-minute commit for 5.16 yesterday that referenced
> the culprit Marcelo specified:
>
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=master&id=c8013355ead68dce152cf426686f8a5f80d88b40
>
> This was for a BCM283x and BCM2711 devices, so I assume it won't help.
> Wild guess (I don't know anything about this area of the kernel):
> Marcelo, do the dts files for your hardware maybe need a similar fix?

I have tried to add "gpio-ranges" to the gpio-controllers in
at91sam9x5.dtsi, but the system deadlocks, because in pinctrl-at91.c,
function at91_pinctrl_probe() we have:

/*
* We need all the GPIO drivers to probe FIRST, or we will not be able
* to obtain references to the struct gpio_chip * for them, and we
* need this to proceed.
*/
for (i = 0; i < gpio_banks; i++)
        if (gpio_chips[i])
                ngpio_chips_enabled++;

        if (ngpio_chips_enabled < info->nactive_banks) {
                dev_warn(&pdev->dev,
                      "All GPIO chips are not registered yet (%d/%d)\n",
                      ngpio_chips_enabled, info->nactive_banks);
               devm_kfree(&pdev->dev, info);
                return -EPROBE_DEFER;
        }

On the other hand, in gpiolib-of.c, function
of_gpiochip_add_pin_range() we have:

if (!pctldev)
        return -EPROBE_DEFER;

In other words, the pinctrl needs all the gpio-controllers, and the
gpio-controllers need the pinctrl. Each returns -EPROBE_DEFER and the
system deadlocks.

>
> Ciao, Thorsten
>
> P.S.: As a Linux kernel regression tracker I'm getting a lot of reports
> on my table. I can only look briefly into most of them. Unfortunately
> therefore I sometimes will get things wrong or miss something important.
> I hope that's not the case here; if you think it is, don't hesitate to
> tell me about it in a public reply, that's in everyone's interest.
>
> BTW, I have no personal interest in this issue, which is tracked using
> regzbot, my Linux kernel regression tracking bot
> (https://linux-regtracking.leemhuis.info/regzbot/). I'm only posting
> this mail to get things rolling again and hence don't need to be CC on
> all further activities wrt to this regression.
>
> #regzbot poke
>

Regards,
Marcelo.

  reply	other threads:[~2022-01-12  0:09 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-17 15:35 Marcelo Roberto Jimenez
2021-12-18  6:28 ` Thorsten Leemhuis
2021-12-20 14:57   ` Bartosz Golaszewski
2021-12-20 15:14     ` Geert Uytterhoeven
2021-12-20 19:24       ` Will McVicker
2021-12-20 20:41         ` Marcelo Roberto Jimenez
2021-12-20 20:41       ` Marcelo Roberto Jimenez
2021-12-20 20:41     ` Marcelo Roberto Jimenez
2022-01-10  7:02       ` Thorsten Leemhuis
2022-01-12  0:09         ` Marcelo Roberto Jimenez [this message]
2022-02-08 12:24           ` Thorsten Leemhuis
2022-02-17 19:11           ` Thierry Reding
2022-02-11  0:02 ` Linus Walleij
2022-02-11 22:36   ` Marcelo Roberto Jimenez
2022-02-12 16:54     ` Linus Walleij
2022-02-13 23:23       ` Marcelo Roberto Jimenez
2022-02-15 21:56         ` Linus Walleij
2022-02-16 14:40           ` Bartosz Golaszewski
2022-03-04  7:13             ` Thorsten Leemhuis
2022-03-07  9:58               ` Bartosz Golaszewski
2022-03-07 10:12                 ` Thorsten Leemhuis
2022-05-20  9:12             ` Thorsten Leemhuis
2022-05-20 17:28               ` Marcelo Roberto Jimenez
2022-03-14 15:55 ` Michael Walle
2022-03-15 15:32   ` Bartosz Golaszewski
2022-03-15 15:45     ` Michael Walle
2022-03-17  8:37       ` Andy Shevchenko
2022-03-17  8:48         ` Michael Walle

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