voyagerfb_i2c_xfer
static int voyagerfb_i2c_xfer(struct voyagerfb_softc *, int, i2c_addr_t,
error = voyagerfb_i2c_xfer(sc, 0, addr, tmp, cmdlen);
error = voyagerfb_i2c_xfer(sc, rw, addr, p + done, chunk);