net: stmmac: Handle disabled MDIO busses from devicetree

[ Upstream commit e23c0d21ce9234fbc31ece35663ababbb83f9347 ]

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@redhat.com>
Reviewed-by: Serge Semin <fancer.lancer@gmail.com>
Link: https://lore.kernel.org/r/20231212-b4-stmmac-handle-mdio-enodev-v2-1-600171acf79f@redhat.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
index fa9e7e7..0542cfd 100644 (file)
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_mdio.c
@@ -591,7 +591,11 @@ 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 == -ENODEV) {
+               err = 0;
+               dev_info(dev, "MDIO bus is disabled\n");
+               goto bus_register_fail;
+       } else if (err) {
                dev_err_probe(dev, err, "Cannot register the MDIO bus\n");
                goto bus_register_fail;
        }