[PATCH net] net: stmmac: Handle disabled MDIO busses from devicetree

[Andrew Halaney]

Many hardware configurations have the MDIO bus disabled, and are instead
using some other MDIO bus to talk to the MAC's phy.

of_mdiobus_register() returns -ENODEV in this case. Let's handle it
gracefully instead of failing to probe the MAC.

Fixes: 47dd7a540b8a (net: add support for STMicroelectronics Ethernet controllers.")
Signed-off-by: Andrew Halaney <ahalaney@xxxxxxxxxx>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
index fa9e7e7040b9..a39be15d41a8 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
@@ -591,7 +591,13 @@ int stmmac_mdio_register(struct net_device *ndev)
 	new_bus->parent = priv->device;
 
 	err = of_mdiobus_register(new_bus, mdio_node);
-	if (err != 0) {
+	if (err) {
+		if (err == -ENODEV) {
+			/* The bus is disabled in the devicetree, that's ok */
+			mdiobus_free(new_bus);
+			return 0;
+		}
+
 		dev_err_probe(dev, err, "Cannot register the MDIO bus\n");
 		goto bus_register_fail;
 	}

---
base-commit: bbd220ce4e29ed55ab079007cff0b550895258eb
change-id: 20231211-b4-stmmac-handle-mdio-enodev-82168de68c6a

Best regards,
-- 
Andrew Halaney <ahalaney@xxxxxxxxxx>