Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Tue, 03 Aug 2021 10:51:11 +0100
Message-ID: <87h7g626wg.wl-maz@kernel.org>
From:   Marc Zyngier <maz@kernel.org>
To:     Kevin Hilman <khilman@baylibre.com>
Cc:     Lee Jones <lee.jones@linaro.org>,
        Neil Armstrong <narmstrong@baylibre.com>,
        Jerome Brunet <jbrunet@baylibre.com>,
        linux-amlogic@lists.infradead.org,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        open list <linux-kernel@vger.kernel.org>,
        Saravana Kannan <saravanak@google.com>
Subject: Re: [PATCH 1/2] irqchip: irq-meson-gpio: make it possible to build as a module
In-Reply-To: <87im0m277h.wl-maz@kernel.org>
References: <20201020072532.949137-1-narmstrong@baylibre.com>
        <20201020072532.949137-2-narmstrong@baylibre.com>
        <7hsga8kb8z.fsf@baylibre.com>
        <CAF2Aj3g6c8FEZb3e1by6sd8LpKLaeN5hsKrrQkZUvh8hosiW9A@mail.gmail.com>
        <87r1hwwier.wl-maz@kernel.org>
        <7h7diwgjup.fsf@baylibre.com>
        <87im0m277h.wl-maz@kernel.org>
User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue)
 FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.1
 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO)
MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue")
Content-Type: text/plain; charset=US-ASCII
Precedence: bulk

On Tue, 03 Aug 2021 10:44:34 +0100,
Marc Zyngier <maz@kernel.org> wrote:

[...]

> This thing keeps failing on my end. It only works if I force the
> irqchip module to be present before the MDIO module is loaded. Here's
> an example:
> 
> root@tiger-roach:~# modprobe mdio_mux_meson_g12a
> [  125.871544] libphy: mdio_mux: probed
> [  125.882575] g12a-mdio_mux ff64c000.mdio-multiplexer: Error: Failed to register MDIO bus for child /soc/bus@ff600000/mdio-multiplexer@4c000/mdio@0
> [  125.892630] libphy: mdio_mux: probed
> 
> Trying to bring up the Ethernet interface will fail. Note that there
> was no attempt to load the irqchip driver.
> 
> root@tiger-roach:~# modprobe -r mdio_mux_meson_g12a
> root@tiger-roach:~# modprobe irq-meson-gpio 
> [  144.983344] meson-gpio-intc ffd0f080.interrupt-controller: 100 to 8 gpio interrupt mux initialized
> root@tiger-roach:~# modprobe mdio_mux_meson_g12a
> [  150.376464] libphy: mdio_mux: probed
> [  150.391039] libphy: mdio_mux: probed
> 
> And it now works.

An additional source of amusement is that this patch allows the
irqchip to be removed from the kernel. It becomes really fun when you
have live interrupts...

	M.

-- 
Without deviation from the norm, progress is not possible.