When the DMA write of the data payload is done, the QDMA writes the
CMPT packet into the CMPT queue. Besides the user defined data, the CMPT packet also
includes some other information, such as error, color, and the length. It also has a
desc_used bit to indicate if the packet
consumes a descriptor. A C2H data packet of immediate-data or marker type does not
consume any descriptor.