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Antoine Tenart says: ==================== net: macb: fix probing of PHY not described in the dt The macb Ethernet driver supports various ways of referencing its network PHY. When a device tree is used the PHY can be referenced with a phy-handle or, if connected to its internal MDIO bus, described in a child node. Some platforms omitted the PHY description while connecting the PHY to the internal MDIO bus and in such cases the MDIO bus has to be scanned "manually" by the macb driver. Prior to the phylink conversion the driver registered the MDIO bus with of_mdiobus_register and then in case the PHY couldn't be retrieved using dt or using phy_find_first (because registering an MDIO bus with of_mdiobus_register masks all PHYs) the macb driver was "manually" scanning the MDIO bus (like mdiobus_register does). The phylink conversion did break this particular case but reimplementing the manual scan of the bus in the macb driver wouldn't be very clean. The solution seems to be registering the MDIO bus based on if the PHYs are described in the device tree or not. There are multiple ways to do this, none is perfect. I chose to check if any of the child nodes of the macb node was a network PHY and based on this to register the MDIO bus with the of_ helper or not. The drawback is boards referencing the PHY through phy-handle, would scan the entire MDIO bus of the macb at boot time (as the MDIO bus would be registered with mdiobus_register). For this solution to work properly of_mdiobus_child_is_phy has to be exported, which means the patch doing so has to be backported to -stable as well. Another possible solution could have been to simply check if the macb node has a child node by counting its sub-nodes. This isn't techically perfect, as there could be other sub-nodes (in practice this should be fine, fixed-link being taken care of in the driver). We could also simply s/of_mdiobus_register/mdiobus_register/ but that could break boards using the PHY description in child node as a selector (which really would be not a proper way to do this...). The real issue here being having PHYs not described in the dt but we have dt backward compatibility, so we have to live with that. ==================== Signed-off-by: David S. Miller <davem@davemloft.net> |
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Linux kernel
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