xdma_fill_descs
desc_num += xdma_fill_descs(sw_desc, *src, *dst, sg_dma_len(sg), desc_num);
desc_num += xdma_fill_descs(sw_desc, *src, *dst, period_size, desc_num);
desc_num += xdma_fill_descs(sw_desc, src_addr, dst_addr, xt->sgl[i].size, desc_num);