TXRX_CSR18
reg = rt2500usb_register_read(rt2x00dev, TXRX_CSR18);
rt2500usb_register_write(rt2x00dev, TXRX_CSR18, reg);
reg = rt2500usb_register_read(rt2x00dev, TXRX_CSR18);
rt2500usb_register_write(rt2x00dev, TXRX_CSR18, reg);