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

[Andrew Lunn <andrew@lunn.ch>]

> > 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