use_dma
.sgt = __sgt_iter(sgl, use_dma(iobase)),
r.sgt = __sgt_iter(__sg_next(r.sgt.sgp), use_dma(iobase));
if (!use_dma(iobase))
if (use_dma(r->iobase))
r->sgt = __sgt_iter(__sg_next(r->sgt.sgp), use_dma(r->iobase));