On Wed, Oct 14, 2015 at 04:12:13PM +0300, Peter Ujfalusi wrote: > @@ -1320,41 +1317,92 @@ static struct dma_async_tx_descriptor *edma_prep_dma_memcpy( > struct dma_chan *chan, dma_addr_t dest, dma_addr_t src, > size_t len, unsigned long tx_flags) > { > - int ret; > + int ret, nslots; > struct edma_desc *edesc; > struct device *dev = chan->device->dev; > struct edma_chan *echan = to_edma_chan(chan); > - unsigned int width; > + unsigned int width, pset_len; > > if (unlikely(!echan || !len)) > return NULL; > > - edesc = kzalloc(sizeof(*edesc) + sizeof(edesc->pset[0]), GFP_ATOMIC); > + if (len < SZ_64K) { > + /* > + * Transfer size less than 64K can be handled with one paRAM > + * slot. ACNT = length > + */ > + width = len; > + pset_len = len; > + nslots = 1; > + } else { > + /* > + * Transfer size bigger than 64K will be handled with maximum of > + * two paRAM slots. > + * slot1: ACNT = 32767, length1: (length / 32767) > + * slot2: the remaining amount of data. > + */ > + width = SZ_32K - 1; > + pset_len = rounddown(len, width); > + /* One slot is enough for lengths multiple of (SZ_32K -1) */ Hmm so does this mean if I have 140K transfer, it will do two 64K for 1st slot and 12K in second slot ? Is there a limit on 'blocks' of 64K we can do here? -- ~Vinod -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html