Re: [PATCH net-next v2 0/3] net: mdio: support dynamic OF device changes

On Mon, Aug 03, 2026 at 05:48:09PM -0600, James Hilliard wrote:

MDIO buses enumerate firmware children only when the bus is registered. A
later devicetree overlay or status transition is ignored, unlike on I2C and
SPI buses. Supporting live reconfiguration also means that population and
removal can race address scanning, PHY attachment and bus teardown.

Patch 1 factors fixed-address child registration and legacy PHY scanning
into helpers shared by initial and dynamic population.

Patch 2 serializes MDIO device-map changes, reserves addresses while
registration is in progress, and coordinates scans, attachment, removal
and bus teardown. Dynamically removed devices remain pinned until bus
teardown, preserving the borrowed-pointer convention of
mdiobus_get_phy().

Patch 3 adds the OF reconfiguration notifier. It supports fixed-address
PHYs and generic MDIO devices, scanned PHY addresses, and Ethernet PHY
packages. It also preflights overlay removal and rejects removal of
attached or in-flight PHYs before their firmware nodes can disappear.

This is a lot of complexity which i think should be avoided by just
getting the bootloader to put the correct nodes in DT.

If this was a hat on top of a SBC, with an EEPROM indicating what the
hat was, then maybe DT overlays would make sense. But from what you
have said, this is a fixed PCB design, nothing hot/cold plugable.

     Andrew