[U-Boot] MDIO_DEVAD_NONE

Hi all,

We are working on porting u-boot to a new board based around the Freescale T4240. We also have a 10G BASE-T PHY on board. We're running into some difficulty bringing up the XFI XGMII interface between the T4240 and the PHY and verifying that it's set up correctly.

One of the things I've noticed is that the genphy functions use MDIO_DEVAD_NONE, which is defined as -1 (0xFFFF as an int). When truncated to 5 bits for an MDIO device address, that's 0x1F. That's not generally a valid MDIO device address, is it?

Reads from this device address, like the one below from genphy_update_link in drivers/net/phy/phy.c:216, return 0xFFFF since the bus is pulled up and there's no driving source in the PHY:

mii_reg = phy_read(phydev, MDIO_DEVAD_NONE, MII_BMSR);

So, in this case, genphy_update_link will falsely report that the link is up if there's no device at the 0x1F MDIO device address.

Is this the intended behavior?

Thanks, Danny