SLAU723A October 2017 – October 2018 MSP432E401Y , MSP432E411Y
Transmit polling can be suspended by either of the following conditions:
If the DMA goes into SUSPEND state because of the first condition, then both the Normal Interrupt Summary (NIS) bit and the Transmit Buffer Unavailable (TU) bit are set in the EMACDMARIS register. If the second condition occurs, the Abnormal Interrupt Summary (AIS) bit and the Transmit Underflow (UNF) bit of the EMACDMARIS register are set and the information is written to Transmit Descriptor 0, causing the suspension.
In both cases, the position in the Transmit list is retained. The retained position is that of the descriptor following the last descriptor closed by the DMA. The driver must explicitly issue a Transmit Poll Demand command after rectifying the suspension case.