On Mon, Mar 30, 2020 at 07:01:36PM +0300, Codrin Ciubotariu wrote:

Some ethernet controllers, such as cadence's macb, have an embedded MDIO.
For this reason, the ethernet PHY nodes are not under an MDIO bus, but
directly under the ethernet node. Since these drivers might use
of_mdiobus_child_is_phy(), we should fix this function by returning false
if a fixed-link is found.

So i assume the problem occurs here:

static int macb_mdiobus_register(struct macb *bp)
{
        struct device_node *child, *np = bp->pdev->dev.of_node;

        /* Only create the PHY from the device tree if at least one PHY is
         * described. Otherwise scan the entire MDIO bus. We do this to support
         * old device tree that did not follow the best practices and did not
         * describe their network PHYs.
         */
        for_each_available_child_of_node(np, child)
                if (of_mdiobus_child_is_phy(child)) {
                        /* The loop increments the child refcount,
                         * decrement it before returning.
                         */
                        of_node_put(child);

                        return of_mdiobus_register(bp->mii_bus, np);
                }

        return mdiobus_register(bp->mii_bus);
}

I think a better solution is

        for_each_available_child_of_node(np, child)
+		if (of_phy_is_fixed_link(child)
+		   continue;
                if (of_mdiobus_child_is_phy(child)) {
                        /* The loop increments the child refcount,
                         * decrement it before returning.
                         */
                        of_node_put(child);

                        return of_mdiobus_register(bp->mii_bus, np);
                }

        return mdiobus_register(bp->mii_bus);
}

This problem is only an issue for macb, so keep the fix local to macb.

	Andrew