Date:   Wed, 17 Aug 2022 15:01:34 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Saravana Kannan <saravanak@...gle.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <brgl@...ev.pl>,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Magnus Damm <magnus.damm@...il.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Daniel Scally <djrscally@...il.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Len Brown <lenb@...nel.org>, Abel Vesa <abel.vesa@...aro.org>,
        Alexander Stein <alexander.stein@...tq-group.com>,
        Tony Lindgren <tony@...mide.com>,
        Sudeep Holla <sudeep.holla@....com>,
        John Stultz <jstultz@...gle.com>,
        Doug Anderson <dianders@...omium.org>,
        Guenter Roeck <linux@...ck-us.net>,
        Android Kernel Team <kernel-team@...roid.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>
Subject: Re: [PATCH v1 0/9] fw_devlink improvements

Hi Saravana,

On Wed, Aug 10, 2022 at 8:00 AM Saravana Kannan <saravanak@...gle.com> wrote:
> This patch series improves fw_devlink in the following ways:
>
> 1. It no longer cares about a fwnode having a "compatible" property. It
>    figures this our more dynamically. The only expectation is that
>    fwnode that are converted to devices actually get probed by a driver
>    for the dependencies to be enforced correctly.
>
> 2. Finer grained dependency tracking. fw_devlink will now create device
>    links from the consumer to the actual resource's device (if it has one,
>    Eg: gpio_device) instead of the parent supplier device. This improves
>    things like async suspend/resume ordering, potentially remove the need
>    for frameworks to create device links, more parallelized async probing,
>    and better sync_state() tracking.
>
> 3. Handle hardware/software quirks where a child firmware node gets
>    populated as a device before its parent firmware node AND actually
>    supplies a non-optional resource to the parent firmware node's
>    device.
>
> 4. Way more robust at cycle handling (see patch for the insane cases).
>
> 5. Stops depending on OF_POPULATED to figure out some corner cases.
>
> 6. Simplifies the work that needs to be done by the firmware specific
>    code.
>
> This took way too long to get done due to typo bugs I had in my rewrite or
> corner cases I had to find and handle. But it's fairly well tested at this
> point and I expect this to work properly.
>
> Abel & Doug,
>
> This should fix your cyclic dependency issues with your display. Can you
> give it a shot please?

Thanks for to your series!

> Geert,
>
> Can you test the renesas stuff I changed please? They should continue
> working like before. Any other sanity test on other hardware would be
> great too.

At first, this series looked like a total disaster, introducing
several regressions[1].

However, after applying the additional fix from
https://lore.kernel.org/lkml/CAGETcx-JUV1nj8wBJrTPfyvM7=Mre5j_vkVmZojeiumUGG6QZQ@mail.gmail.com
all regressions[1] went away, and /sys/kernel/debug/devices_deferred
is empty again.

Note that the Ethernet PHY interrupt on Koelsch is not fixed, so the issue from
https://lore.kernel.org/all/CAMuHMdWo_wRwV-i_iyTxVnEsf3Th9GBAG+wxUQMQGnw1t2ijTg@mail.gmail.com/
is still present.

Summary: while this series (+ the additional fix) doesn't seem to
introduce any regressions on Renesas ARM platforms, it doesn't seem
to fix anything for me neither.

Tested-by: Geert Uytterhoeven <geert+renesas@...der.be>

[1]

R-Mobile APE6 (ape6evm):
    No "deferred probe pending" messages?

    # cat /sys/kernel/debug/devices_deferred
    ee120000.mmc platform: wait for supplier sd1
    ee100000.mmc platform: wait for supplier sd0
    ee200000.mmc platform: wait for supplier mmc0
    keyboard platform: wait for supplier keyboard

R-Mobile A1 (armadillo-800-eva):
    No soundcards found.
    platform backlight: deferred probe pending
    i2c 0-0030: deferred probe pending (RTC)
    platform sound: deferred probe pending
    platform fe1f0000.sound: deferred probe pending
    platform keyboard: deferred probe pending (gpio-keys)
    platform e6850000.mmc: deferred probe pending (SDHI)
    platform e6bd0000.mmc: deferred probe pending (SDHI)

    # cat /sys/kernel/debug/devices_deferred
    backlight platform: wait for supplier backlight
    0-0030 i2c: wait for supplier rtc
    sound asoc-simple-card: parse error
    fe1f0000.sound platform: wait for supplier sounda
    keyboard platform: wait for supplier keyboard
    e6850000.mmc platform: wait for supplier sd0
    e6bd0000.mmc platform: wait for supplier mmc0

SH-Mobile AG5 (kzm9g):
    No soundcards found.
    platform sound: deferred probe pending
    platform ec230000.sound: deferred probe pending

    # cat /sys/kernel/debug/devices_deferred
    sound asoc-simple-card: parse error
    ec230000.sound platform: wait for supplier sounda

    Note: This is the only board where gpio-keys still works!

R-Car M2-W (koelsch):

    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)

    i2c-demux-pinctrl i2c-13: Failed to create device link with hdmi-in
    i2c-demux-pinctrl i2c-13: Failed to create device link with hdmi-out

    No soundcards found.

    Some I2C-busses are missing, but not listed in
/sys/kernel/debug/devices_deferred?
    /devices/platform/soc/e6518000.i2c
    /devices/platform/soc/e6530000.i2c
    /devices/platform/soc/e6520000.i2c

    platform keyboard: deferred probe pending
    platform sound: deferred probe pending
    platform feb00000.display: deferred probe pending

    # cat /sys/kernel/debug/devices_deferred
    keyboard platform: wait for supplier keyboard
    sound asoc-simple-card: parse error
    feb00000.display rcar-du: failed to initialize DRM/KMS

R-Car Gen3 (Salvator-X(S), Ebisu)
    platform keys: deferred probe pending (gpio-keys)

    # cat /sys/kernel/debug/devices_deferred
    keys platform: wait for supplier keys

RZ/A (rskrza1, rza2mevb)
    No "deferred probe pending" messages?
    # cat /sys/kernel/debug/devices_deferred
    keyboard platform: wait for supplier keyboard

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-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

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