XILINX_DMA_REG_TAILDESC
xilinx_write(chan, XILINX_DMA_REG_TAILDESC,
xilinx_write(chan, XILINX_DMA_REG_TAILDESC,
xilinx_write(chan, XILINX_DMA_REG_TAILDESC,
dma_ctrl_read(chan, XILINX_DMA_REG_TAILDESC));