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From:   Geert Uytterhoeven <geert@linux-m68k.org>
Date:   Tue, 2 Feb 2021 08:55:02 +0100
Message-ID: <CAMuHMdWo0Dpf_GwT1WrGk9f3v7-KX86eR2wgNtXkqoN0t_CLag@mail.gmail.com>
Subject: Re: [PATCH v1 0/2] Make fw_devlink=on more forgiving
To:     Saravana Kannan <saravanak@google.com>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Marek Szyprowski <m.szyprowski@samsung.com>,
        Marc Zyngier <maz@kernel.org>,
        Tudor Ambarus <Tudor.Ambarus@microchip.com>,
        Linus Walleij <linus.walleij@linaro.org>,
        Bartosz Golaszewski <bgolaszewski@baylibre.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Android Kernel Team <kernel-team@android.com>,
        Wolfram Sang <wsa+renesas@sang-engineering.com>,
        Linux-Renesas <linux-renesas-soc@vger.kernel.org>
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Hi Saravana,

On Tue, Feb 2, 2021 at 4:01 AM Saravana Kannan <saravanak@google.com> wrote:
> On Mon, Feb 1, 2021 at 2:40 AM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > On Sat, Jan 30, 2021 at 5:09 AM Saravana Kannan <saravanak@google.com> wrote:
> > > On Fri, Jan 29, 2021 at 8:03 PM Saravana Kannan <saravanak@google.com> wrote:
> > > > This patch series solves two general issues with fw_devlink=on
> > > >
> > > > Patch 1/2 addresses the issue of firmware nodes that look like they'll
> > > > have struct devices created for them, but will never actually have
> > > > struct devices added for them. For example, DT nodes with a compatible
> > > > property that don't have devices added for them.
> > > >
> > > > Patch 2/2 address (for static kernels) the issue of optional suppliers
> > > > that'll never have a driver registered for them. So, if the device could
> > > > have probed with fw_devlink=permissive with a static kernel, this patch
> > > > should allow those devices to probe with a fw_devlink=on. This doesn't
> > > > solve it for the case where modules are enabled because there's no way
> > > > to tell if a driver will never be registered or it's just about to be
> > > > registered. I have some other ideas for that, but it'll have to come
> > > > later thinking about it a bit.
> > > >
> > > > These two patches might remove the need for several other patches that
> > > > went in as fixes for commit e590474768f1 ("driver core: Set
> > > > fw_devlink=on by default"), but I think all those fixes are good
> > > > changes. So I think we should leave those in.
> > > >
> > > > Marek, Geert,
> > > >
> > > > Can you try this series on a static kernel with your OF_POPULATED
> > > > changes reverted? I just want to make sure these patches can identify
> > > > and fix those cases.
> > > >
> > > > Tudor,
> > > >
> > > > You should still make the clock driver fix (because it's a bug), but I
> > > > think this series will fix your issue too (even without the clock driver
> > > > fix). Can you please give this a shot?
> > >
> > > Marek, Geert, Tudor,
> > >
> > > Forgot to say that this will probably fix your issues only in a static
> > > kernel. So please try this with a static kernel. If you can also try
> > > and confirm that this does not fix the issue for a modular kernel,
> > > that'd be good too.
> >
> > Thanks for your series!
> >
> > For the modular case, this series has no impact, as expected (i.e. fails
> > to boot, no I/O devices probed).
> > With modules disabled, both r8a7791/koelsch and r8a77951/salvator-xs
> > seem to boot fine, except for one issue on koelsch:
>
> Thanks a lot for testing the series!
>
> Regarding the koelsch issue, do you not see it with your OF_POPULATED
> fix for rcar-sysc driver? But only see if you revert it and use this
> series?

I've just rechecked, and with fw_devlink=on, and my OF_POPULATED
fir for rcar-sysc, i2c-demux-pinctrl works, both with modules enabled
and disabled.

> > dmesg:
> >
> >     +i2c-demux-pinctrl i2c-12: failed to setup demux-adapter 0 (-19)
> >     +i2c-demux-pinctrl i2c-13: failed to setup demux-adapter 0 (-19)
> >     +i2c-demux-pinctrl i2c-14: failed to setup demux-adapter 0 (-19)
> >
> >     -  #0: rsnd-dai.0-ak4642-hifi
> >     +  No soundcards found.
> >
> > regulator_summary:
> >
> >     -13-0050-vcc                   0    0mA     0mV     0mV
> >     -13-0039-dvdd-3v               1    0mA     0mV     0mV
> >     -13-0039-bgvdd                 1    0mA     0mV     0mV
> >     -13-0039-pvdd                  1    0mA     0mV     0mV
> >     -13-0039-dvdd                  1    0mA     0mV     0mV
> >     -13-0039-avdd                  1    0mA     0mV     0mV
> >
> > pm_genpd_summary:
> >
> >     -/devices/platform/soc/e6518000.i2c  suspended                  0
> >     -/devices/platform/soc/e6530000.i2c  suspended                  0
> >     -/devices/platform/soc/e6520000.i2c  suspended                  0
> >
> > These are all symptoms of the same issue: i2c buses and devices are not
> > probed, due to the use of the i2c demuxer.
> > I guess the fw_devlink tracker doesn't consider "i2c-parent" links?
>
> No, it doesn't parse "i2c-parent". Ugh... looked at it. It's going to
> be a problem to parse because it requires the parents to be disbled in
> DT and then fixes them up during run time. fw_devlink can handle DT
> overlay changing a specific node, but the problem is that the consumer
> DT node doesn't get changed. So the i2c-parent will first be parsed,
> fw_devlink will notice they are disabled, so it'll ignore them. Then
> those nodes are enabled, but the i2c-parent isn't reparsed because the
> consumer isn't updated.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds