net: mdio-mux: Handle -EPROBE_DEFER correctly

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>

diff --git a/drivers/net/mdio/mdio-mux.c b/drivers/net/mdio/mdio-mux.c
index 13035e2..ebd001f 100644 (file)
--- 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;