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From:   Saravana Kannan <saravanak@google.com>
Date:   Wed, 10 Feb 2021 00:20:48 -0800
Message-ID: <CAGETcx-UaYEeYVXg0sd4=9t2zbBe8YH1LOoOms9ANGix=Zmypw@mail.gmail.com>
Subject: Re: [PATCH v1 5/5] driver core: Set fw_devlink=on by default
To:     Guenter Roeck <linux@roeck-us.net>
Cc:     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>,
        Marc Zyngier <maz@kernel.org>
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On Tue, Feb 9, 2021 at 9:54 PM Guenter Roeck <linux@roeck-us.net> wrote:
>
> On Thu, Dec 17, 2020 at 07:17:03PM -0800, Saravana Kannan wrote:
> > Cyclic dependencies in some firmware was one of the last remaining
> > reasons fw_devlink=on couldn't be set by default. Now that cyclic
> > dependencies don't block probing, set fw_devlink=on by default.
> >
> > Setting fw_devlink=on by default brings a bunch of benefits (currently,
> > only for systems with device tree firmware):
> > * Significantly cuts down deferred probes.
> > * Device probe is effectively attempted in graph order.
> > * Makes it much easier to load drivers as modules without having to
> >   worry about functional dependencies between modules (depmod is still
> >   needed for symbol dependencies).
> >
> > If this patch prevents some devices from probing, it's very likely due
> > to the system having one or more device drivers that "probe"/set up a
> > device (DT node with compatible property) without creating a struct
> > device for it.  If we hit such cases, the device drivers need to be
> > fixed so that they populate struct devices and probe them like normal
> > device drivers so that the driver core is aware of the devices and their
> > status. See [1] for an example of such a case.
> >
> > [1] - https://lore.kernel.org/lkml/CAGETcx9PiX==mLxB9PO8Myyk6u2vhPVwTMsA5NkD-ywH5xhusw@mail.gmail.com/
> > Signed-off-by: Saravana Kannan <saravanak@google.com>
>
> This patch breaks nios2 boot tests in qemu. The system gets stuck when
> trying to reboot. Reverting this patch fixes the problem. Bisect log
> is attached.

Thanks for the report Guenter. Can you please try this series?
https://lore.kernel.org/lkml/20210205222644.2357303-1-saravanak@google.com/

It's in driver-core-testing too if that's easier.

-Saravana