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    Subject[PATCH 5.13 067/127] net: mdio-mux: Handle -EPROBE_DEFER correctly
    Date
    From: Saravana Kannan <saravanak@google.com>

    [ Upstream commit 7bd0cef5dac685f09ef8b0b2a7748ff42d284dc7 ]

    When registering mdiobus children, if we get an -EPROBE_DEFER, we shouldn't
    ignore it and continue registering the rest of the mdiobus children. This
    would permanently prevent the deferring child mdiobus from working instead
    of reattempting it in the future. So, if a child mdiobus needs to be
    reattempted in the future, defer the entire mdio-mux initialization.

    This fixes the issue where PHYs sitting under the mdio-mux aren't
    initialized correctly if the PHY's interrupt controller is not yet ready
    when the mdio-mux is being probed. Additional context in the link below.

    Fixes: 0ca2997d1452 ("netdev/of/phy: Add MDIO bus multiplexer support.")
    Link: https://lore.kernel.org/lkml/CAGETcx95kHrv8wA-O+-JtfH7H9biJEGJtijuPVN0V5dUKUAB3A@mail.gmail.com/#t
    Signed-off-by: Saravana Kannan <saravanak@google.com>
    Reviewed-by: Andrew Lunn <andrew@lunn.ch>
    Acked-by: Marc Zyngier <maz@kernel.org>
    Tested-by: Marc Zyngier <maz@kernel.org>
    Acked-by: Kevin Hilman <khilman@baylibre.com>
    Tested-by: Kevin Hilman <khilman@baylibre.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/net/mdio/mdio-mux.c | 8 ++++++--
    1 file changed, 6 insertions(+), 2 deletions(-)

    diff --git a/drivers/net/mdio/mdio-mux.c b/drivers/net/mdio/mdio-mux.c
    index d6ed9033339c..3dde0c2b3e09 100644
    --- a/drivers/net/mdio/mdio-mux.c
    +++ b/drivers/net/mdio/mdio-mux.c
    @@ -175,11 +175,15 @@ int mdio_mux_init(struct device *dev,
    cb->mii_bus->write = mdio_mux_write;
    r = of_mdiobus_register(cb->mii_bus, child_bus_node);
    if (r) {
    + mdiobus_free(cb->mii_bus);
    + if (r == -EPROBE_DEFER) {
    + ret_val = r;
    + goto err_loop;
    + }
    + devm_kfree(dev, cb);
    dev_err(dev,
    "Error: Failed to register MDIO bus for child %pOF\n",
    child_bus_node);
    - mdiobus_free(cb->mii_bus);
    - devm_kfree(dev, cb);
    } else {
    cb->next = pb->children;
    pb->children = cb;
    --
    2.30.2
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