Without defining this signal, the UART lines receive garbage data
when no cable is connected to the J4 USB UART port.
The GPIO9 is enabled in the reference base design along with the
4MA CURRENT_STRENGTH constraint on the UART pins
Ignore the following critical warning on DMAC instance:
Critical Warning (15003): "mixed_port_feed_through_mode" parameter of RAM atom
system_bd:i_system_bd|axi_dmac:axi_dmac_0|axi_dmac_transfer:i_transfer| \
dmac_request_arb:i_request_arb|dmac_dest_mm_axi:i_dest_dma_mm| \
altsyncram:bl_mem_rtl_0|altsyncram_0tp1:auto_generated|ram_block1a1
cannot have value "old" when different read and write clocks are used.
Adrian Costina
Istvan Csomortani
Stanca Pop