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Message-ID: <712cb4237f1dbb8d1104736e20713ba457444650.camel@suse.de>
Subject: Re: [PATCH v1 0/5] Enable fw_devlink=on by default
From:   Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
To:     Saravana Kannan <saravanak@google.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "Rafael J. Wysocki" <rafael@kernel.org>
Cc:     kernel-team@android.com, linux-kernel@vger.kernel.org,
        Jisheng Zhang <Jisheng.Zhang@synaptics.com>,
        Kevin Hilman <khilman@baylibre.com>,
        John Stultz <john.stultz@linaro.org>,
        Marc Zyngier <maz@kernel.org>
Date:   Wed, 13 Jan 2021 12:44:34 +0100
In-Reply-To: <20201218031703.3053753-1-saravanak@google.com>
References: <20201218031703.3053753-1-saravanak@google.com>
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On Thu, 2020-12-17 at 19:16 -0800, Saravana Kannan wrote:
> As discussed in LPC 2020, cyclic dependencies in firmware that couldn't
> be broken using logic was one of the last remaining reasons
> fw_devlink=3Don couldn't be set by default.
>=20
> This series changes fw_devlink so that when a cyclic dependency is found
> in firmware, the links between those devices fallback to permissive mode
> behavior. This way, the rest of the system still benefits from
> fw_devlink, but the ambiguous cases fallback to permissive mode.
>=20
> Setting fw_devlink=3Don 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
> =C2=A0=C2=A0worry about functional dependencies between modules (depmod i=
s still
> =C2=A0=C2=A0needed for symbol dependencies).

FWIW I don't see any issues with this on Raspberry Pi 4 :).

Regards,
Nicolas


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