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From:   Geert Uytterhoeven <geert@linux-m68k.org>
Date:   Sat, 6 Feb 2021 20:41:22 +0100
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Subject: Re: [PATCH v4 0/8] Make fw_devlink=on more forgiving
To:     Saravana Kannan <saravanak@google.com>
Cc:     Jonathan Corbet <corbet@lwn.net>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Kevin Hilman <khilman@kernel.org>,
        Ulf Hansson <ulf.hansson@linaro.org>,
        Len Brown <len.brown@intel.com>, Len Brown <lenb@kernel.org>,
        Pavel Machek <pavel@ucw.cz>,
        Michael Turquette <mturquette@baylibre.com>,
        Stephen Boyd <sboyd@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Frank Rowand <frowand.list@gmail.com>,
        Marc Zyngier <maz@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        "open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux PM list <linux-pm@vger.kernel.org>,
        linux-clk <linux-clk@vger.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>,
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        Marek Szyprowski <m.szyprowski@samsung.com>,
        Android Kernel Team <kernel-team@android.com>
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Hi Saravana,

On Fri, Feb 5, 2021 at 11:26 PM Saravana Kannan <saravanak@google.com> wrote:
> There are a lot of devices/drivers where they never have a struct device
> created for them or the driver initializes the hardware without ever
> binding to the struct device.
>
> This series is intended to avoid any boot regressions due to such
> devices/drivers when fw_devlink=on and also address the handling of
> optional suppliers.

Thanks for your series!

> Patch 5 sets up a generic API to handle drivers that never bind with
> their devices.
>
> Patch 6 through 8 update different frameworks to use the new API.

>   driver core: fw_devlink: Handle suppliers that don't use driver core
>   irqdomain: Mark fwnodes when their irqdomain is added/removed
>   PM: domains: Mark fwnodes when their powerdomain is added/removed
>   clk: Mark fwnodes when their clock provider is added/removed

I take it this is an automatic alternative for letting drivers set the
OF_POPULATED flag manually?

Is this actually safe?  It's not uncommon for a driver to register
multiple providers, sometimes even of different types (clock, genpd,
irq, reset[1], ...).
Can you be sure consumer drivers do not start probing while their
dependency is still busy registering providers?

[1] Which brings my attention to the fact that devlink does not consider
    "resets" properties yet.

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