FLUSH_FIFO
FLUSH_FIFO(host);
outb(FLUSH_FIFO, port_base + CMD_REG);
outb(FLUSH_FIFO, port_base + CMD_REG);
outb(FLUSH_FIFO, port_base + CMD_REG);
outb(FLUSH_FIFO, port_base + CMD_REG); /* reset the fifos */