MLX_V4_MAILBOX
bus_space_barrier(sc->mlx_btag, sc->mlx_bhandle, MLX_V4_MAILBOX, MLX_V4_MAILBOX_LENGTH,
#define MLX_V4_PUT_MAILBOX(sc, idx, val) bus_space_write_1(sc->mlx_btag, sc->mlx_bhandle, MLX_V4_MAILBOX + idx, val)