MAX_LEN_CFG
reg = rt2800_register_read(rt2x00dev, MAX_LEN_CFG);
rt2800_register_write(rt2x00dev, MAX_LEN_CFG, reg);
reg = rt2800_register_read(rt2x00dev, MAX_LEN_CFG);
rt2800_register_write(rt2x00dev, MAX_LEN_CFG, reg);