LDMA_DESC_EN
desc->sg[sg_index - 1].hw->ndesc_addr = ldma_sg->llp | LDMA_DESC_EN;
desc->sg[sg_len - 1].hw->ndesc_addr &= ~LDMA_DESC_EN;
desc->sg[num_periods - 1].hw->ndesc_addr = desc->sg[0].llp | LDMA_DESC_EN;