Messages in this thread | | | Date | Mon, 2 Jan 2012 11:08:17 +0100 | Subject | Re: [PATCH] dmaengine: Add support for MEMCPY for imx-dma. | From | javier Martin <> |
| |
Hi Vinod, thank you for your review.
On 23 December 2011 18:38, Vinod Koul <vinod.koul@intel.com> wrote: >> @@ -328,6 +329,37 @@ static struct dma_async_tx_descriptor *imxdma_prep_dma_cyclic( >> return &imxdmac->desc; >> } >> >> +static struct dma_async_tx_descriptor *imxdma_prep_dma_memcpy( >> + struct dma_chan *chan, dma_addr_t dest, >> + dma_addr_t src, size_t len, unsigned long flags) >> +{ >> + struct imxdma_channel *imxdmac = to_imxdma_chan(chan); >> + struct imxdma_engine *imxdma = imxdmac->imxdma; >> + int ret; >> + >> + dev_dbg(imxdma->dev, "%s channel: %d src=0x%x dst=0x%x len=%d\n", >> + __func__, imxdmac->channel, src, dest, len); >> + >> + if (imxdmac->status == DMA_IN_PROGRESS) >> + return NULL; >> + >> + imxdmac->status = DMA_IN_PROGRESS; > why? prepare doesn't mean DMA is in progress. You can get multiple > descriptors for same channel by calling prepare multiple times. > Even one descriptor can be memcpy whereas other is slave... > In issue_pending this should be moved to DMA_IN_PROGRESS
According to the original developer of this file it only supports a single descriptor. Please, take a look at the following function:
static void imxdma_issue_pending(struct dma_chan *chan) { /* * Nothing to do. We only have a single descriptor */ }
Also, the same behavior is present in the other prepare functions: "imxdma_prep_slave_sg" and "imxdma_prep_dma_cyclic".
I think the less painful approach here is merging my patch so that multiple descriptors support can be added later.
-- Javier Martin Vista Silicon S.L. CDTUC - FASE C - Oficina S-345 Avda de los Castros s/n 39005- Santander. Cantabria. Spain +34 942 25 32 60 www.vista-silicon.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |