pxa2x0_dma_desc
struct pxa2x0_dma_desc *dd;
#define DMAC_N_DESCS ((PAGE_SIZE * 2) / sizeof(struct pxa2x0_dma_desc))
#define DMAC_DESCS_SIZE (DMAC_N_DESCS * sizeof(struct pxa2x0_dma_desc))
struct pxa2x0_dma_desc *dd;
sc->sc_segs.ds_addr + (sizeof(struct pxa2x0_dma_desc) * i);
struct pxa2x0_dma_desc *d_desc;