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In-Reply-To: <f3683601-66db-ffe3-9066-ac94a9372727@nvidia.com>
From:   Saravana Kannan <saravanak@google.com>
Date:   Fri, 15 Jan 2021 09:44:15 -0800
Message-ID: <CAGETcx-3wjcmTgrqEyDiHx7dj0m3ME8PmVyGm2kLjFoUT=bfAQ@mail.gmail.com>
Subject: Re: [PATCH v1 0/5] Enable fw_devlink=on by default
To:     Jon Hunter <jonathanh@nvidia.com>
Cc:     Marc Zyngier <maz@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Android Kernel Team <kernel-team@android.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Jisheng Zhang <Jisheng.Zhang@synaptics.com>,
        Kevin Hilman <khilman@baylibre.com>,
        John Stultz <john.stultz@linaro.org>,
        Nicolas Saenz Julienne <nsaenzjulienne@suse.de>,
        linux-tegra <linux-tegra@vger.kernel.org>
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On Fri, Jan 15, 2021 at 8:13 AM Jon Hunter <jonathanh@nvidia.com> wrote:
>
>
> On 14/01/2021 21:50, Saravana Kannan wrote:
> > On Thu, Jan 14, 2021 at 10:55 AM Jon Hunter <jonathanh@nvidia.com> wrote:
> >>
> >>
> >> On 14/01/2021 16:52, Saravana Kannan wrote:
> >>
> >> ...
> >>
> >>> Thanks! I think you forgot to enable those logs though. Also, while
> >>> you are at it, maybe enable the logs in device_link_add() too please?
> >>
> >>
> >> Sorry try this one.
> >>
> >> Cheers
> >> Jon
> >
> > Phew! That took almost 4 hours to debug on the side! I think I figured
> > it out. Can you try this patch? If it works or improves things, I'll
> > explain why it helps.
> >
> > -Saravana
> >
> > diff --git a/drivers/of/property.c b/drivers/of/property.c
> > index 5f9eed79a8aa..1c8c65c4a887 100644
> > --- a/drivers/of/property.c
> > +++ b/drivers/of/property.c
> > @@ -1258,6 +1258,8 @@ DEFINE_SIMPLE_PROP(pinctrl5, "pinctrl-5", NULL)
> >  DEFINE_SIMPLE_PROP(pinctrl6, "pinctrl-6", NULL)
> >  DEFINE_SIMPLE_PROP(pinctrl7, "pinctrl-7", NULL)
> >  DEFINE_SIMPLE_PROP(pinctrl8, "pinctrl-8", NULL)
> > +DEFINE_SIMPLE_PROP(gpio_compat, "gpio", "#gpio-cells")
> > +DEFINE_SIMPLE_PROP(gpios_compat, "gpios", "#gpio-cells")
> >  DEFINE_SUFFIX_PROP(regulators, "-supply", NULL)
> >  DEFINE_SUFFIX_PROP(gpio, "-gpio", "#gpio-cells")
> >  DEFINE_SUFFIX_PROP(gpios, "-gpios", "#gpio-cells")
> > @@ -1296,6 +1298,8 @@ static const struct supplier_bindings
> > of_supplier_bindings[] = {
> >         { .parse_prop = parse_pinctrl6, },
> >         { .parse_prop = parse_pinctrl7, },
> >         { .parse_prop = parse_pinctrl8, },
> > +       { .parse_prop = parse_gpio_compat, },
> > +       { .parse_prop = parse_gpios_compat, },
> >         { .parse_prop = parse_regulators, },
> >         { .parse_prop = parse_gpio, },
> >         { .parse_prop = parse_gpios, },
> >
>
> Thanks, that worked!
>
> Tested-by: Jon Hunter <jonathanh@nvidia.com>
>
> Thanks for digging into that one. Would have taken me more than 4 hours!

Thanks for testing. What was happening was that there was a cycle of
2-3 devices. A -(depends on)-> B -> C -> A.

And fw_devlink only understood A -> B since the rest were the gpio
bindings I added above. Without fw_devlink seeing the cycle, it can't
do cycle workarounds. So C's driver was deferring probe waiting on A
and none of them probed.

Once I added these and made the cycle visible to fw_devlink, it
handled it fine (basically between A, B and C, the device links don't
affect probe order anymore).


-Saravana