[PATCH 1/4] net: mvneta: driver for Marvell Armada 370/XP network unit

quoted

I think we normally put the phy into a separate device node on an
mdio bus and then use the of_phy_* functions to connect it to
the ethernet device.

Even though it may not be a convincing argument, none of the existing DT
files in arch/arm/boot/dts seem to instantiate a separate PHY device
and a proper MDIO bus. However, the PowerPC platforms indeed make this
distinction a lot clearer.

However, this network unit has a clever MAC that autonomously queries
the PHY for the link status, and reports changes (link, duplex, speed)
in the form of MAC interrupts and MAC registers. Therefore, for basic
operation, there is no need for a separate PHY driver nor to expose the
MDIO bus in any way. The only thing needed is the PHY address, which is
filled into a register of the MAC so that it can start its automatic
query of the PHY.

Hi Thomas

I've used Marvell switch chipsets, which have a phy polling unit,
PPU. This sounds very similar. You can do a lot with the PPU, but when
you want to configure subsets of auto-negotiation rates/duplex modes,
or fixed speeds/duplex modes, the PPU could not do it. You had to
disable the PPU and configure the PHY directly.

I see you have some of the ethtools API calls implemented, but not the
ones needed for auto-neg and rates/duplex mode configurations. Does
the neta PPU support this, or will you need to export the MDIO bus for
these sorts of configuration options?

   Thanks
      Andrew