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Date:   Mon,  7 Feb 2022 18:15:48 +0200
From:   Vladimir Oltean <>
Cc:     Florian Fainelli <>,
        Andrew Lunn <>,
        Vivien Didelot <>,
        Vladimir Oltean <>,
        "David S. Miller" <>,
        Jakub Kicinski <>,
        Hauke Mehrtens <>,
        Sean Wang <>,
        Landen Chao <>,
        DENG Qingfang <>,
        Matthias Brugger <>,
        Claudiu Manoil <>,
        Alexandre Belloni <>,,
        Oleksij Rempel <>,
        Bartosz Golaszewski <>,
        Laurentiu Tudor <>,
        Rafael Richter <>,
        Daniel Klauer <>
Subject: [PATCH net 2/7] net: dsa: ar9331: register the mdiobus under devres

As explained in commits:
74b6d7d13307 ("net: dsa: realtek: register the MDIO bus under devres")
5135e96a3dd2 ("net: dsa: don't allocate the slave_mii_bus using devres")

mdiobus_free() will panic when called from devm_mdiobus_free() <-
devres_release_all() <- __device_release_driver(), and that mdiobus was
not previously unregistered.

The ar9331 is an MDIO device, so the initial set of constraints that I
thought would cause this (I2C or SPI buses which call ->remove on
->shutdown) do not apply. But there is one more which applies here.

If the DSA master itself is on a bus that calls ->remove from ->shutdown
(like dpaa2-eth, which is on the fsl-mc bus), there is a device link
between the switch and the DSA master, and device_links_unbind_consumers()
will unbind the ar9331 switch driver on shutdown.

So the same treatment must be applied to all DSA switch drivers, which
is: either use devres for both the mdiobus allocation and registration,
or don't use devres at all.

The ar9331 driver doesn't have a complex code structure for mdiobus
removal, so just replace of_mdiobus_register with the devres variant in
order to be all-devres and ensure that we don't free a still-registered

Fixes: ac3a68d56651 ("net: phy: don't abuse devres in devm_mdiobus_register()")
Signed-off-by: Vladimir Oltean <>
 drivers/net/dsa/qca/ar9331.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/net/dsa/qca/ar9331.c b/drivers/net/dsa/qca/ar9331.c
index 3bda7015f0c1..e5098cfe44bc 100644
--- a/drivers/net/dsa/qca/ar9331.c
+++ b/drivers/net/dsa/qca/ar9331.c
@@ -378,7 +378,7 @@ static int ar9331_sw_mbus_init(struct ar9331_sw_priv *priv)
 	if (!mnp)
 		return -ENODEV;
-	ret = of_mdiobus_register(mbus, mnp);
+	ret = devm_of_mdiobus_register(dev, mbus, mnp);
 	if (ret)
 		return ret;
@@ -1066,7 +1066,6 @@ static void ar9331_sw_remove(struct mdio_device *mdiodev)
-	mdiobus_unregister(priv->mbus);

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