> Again, I don't think Linux has generic support for overwriting (or > even describing) the operating mode of a PHY, although maybe that's a > direction we would want to push the discussion towards. RGMII to > copper, RGMII to fiber, SGMII to copper, copper to fiber (media > converter), even RGMII to SGMII (RTL8211FS supports this) - lots of > modes, and this is only for gigabit PHYs...
This is something Russell King has PHYLINK patches for, which have not yet been merged. There are some boards which use a PHY as a media converter, placed between the MAC and an SFP. Andrew