or not the OS has to wait for RX_RDY or TX_RDY to be set before the OS sets
the control code in the control/status register. Looking at the interface
design, it seems that RX_RDY and TX_RDY are probably there to protect
access to the data register and have nothing to do with the control/status
register. Nevertheless, try to take what I think is the more conservative
approach and always wait for the appropriate [TR]X_RDY flag to be set
before writing any of the WR_NEXT, WR_END, RD_START, or RD_NEXT control
codes to the control/status register.