linux-kernel - Re: [PATCH v4 0/8] Make fw

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Message-ID: <CAMuHMdXo+ShM3Ct2OSCscJwaLJ4rbytpA14=dR5q+3F9kJjNfw@mail.gmail.com>
Date:   Sat, 6 Feb 2021 20:41:22 +0100
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Saravana Kannan <saravanak@...gle.com>
Cc:     Jonathan Corbet <corbet@....net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Kevin Hilman <khilman@...nel.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Len Brown <len.brown@...el.com>, Len Brown <lenb@...nel.org>,
        Pavel Machek <pavel@....cz>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Marc Zyngier <maz@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        "open list:DOCUMENTATION" <linux-doc@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux PM list <linux-pm@...r.kernel.org>,
        linux-clk <linux-clk@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Android Kernel Team <kernel-team@...roid.com>
Subject: Re: [PATCH v4 0/8] Make fw_devlink=on more forgiving

Hi Saravana,

On Fri, Feb 5, 2021 at 11:26 PM Saravana Kannan <saravanak@...gle.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@...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