Force 100Mpbs full duplex on sunhme

FC3 w/ kernel 2.6.12-1.1381_FC3smp

I have a Sun Quad Fast Ethernet PCI card, recognised by the kernel as a Sun
HappyMeal via the driver sunhme.

I can't find any options to force the ports to 100 Mpbs full-duplex. There's
no documented options for the sunhme driver in Documentation/networking
under the kernel source. Currently, it is using 100 Mbps half-duplex only.

It's also not configurable via mii-tool:

/sbin/mii-tool -v -v eth1
SIOCGMIIPHY on 'eth1' failed: Operation not supported


Any ideas ?