GEM_MAC_EXCESS_COLL_CNT
v = bus_space_read_4(t, mac, GEM_MAC_EXCESS_COLL_CNT) +
bus_space_write_4(t, mac, GEM_MAC_EXCESS_COLL_CNT, 0);
bus_space_write_4(t, h, GEM_MAC_EXCESS_COLL_CNT, 0);