i810_read_dac
i810_read_dac(regno * 8, red, green, blue, mmio);
i810_read_dac(regno * 8, red, &tmp, blue, mmio);
i810_read_dac(regno * 4, &tmp, green, &tmp, mmio);
i810_read_dac(regno, red, green, blue, mmio);
i810_read_dac((u8) (regno*4), &r, &g, &b, mmio);