For DMA mode operation, follow these steps.
1.Select the generic Quad-SPI controller by writing a 1 to the generic_qspi_sel register bit.
2.Set the mode_en bits = 2'b10 of the GQSPI_CFG register.
3.Write the command, address, dummies in the generic FIFO using the read request.
4.The generic Quad-SPI controller sends the command as programmed in the generic FIFO and reads the data into the RXFIFO.
5.The DMA controller issues DMA requests using the AXI master interface and sends the RXFIFO data.
When two flash devices are connected in stacked mode, the generic Quad-SPI controller checks for the data bus select field of the generic FIFO and sends the requests accordingly.