dmaengine: stm32-dma: enable descriptor_reuse

Enable client to resubmit already processed descriptors
in order to save descriptor creation time.
Signed-off-by: NPierre-Yves MORDRET <pierre-yves.mordret@st.com>
Signed-off-by: NAmelie Delaunay <amelie.delaunay@st.com>
Link: https://lore.kernel.org/r/20200129153628.29329-5-amelie.delaunay@st.comSigned-off-by: NVinod Koul <vkoul@kernel.org>

drivers/dma/stm32-dma.c

@@ -554,6 +554,7 @@ static void stm32_dma_start_transfer(struct stm32_dma_chan *chan)
 	sg_req = &chan->desc->sg_req[chan->next_sg];
 	reg = &sg_req->chan_reg;
 
+	reg->dma_scr &= ~STM32_DMA_SCR_EN;
 	stm32_dma_write(dmadev, STM32_DMA_SCR(chan->id), reg->dma_scr);
 	stm32_dma_write(dmadev, STM32_DMA_SPAR(chan->id), reg->dma_spar);
 	stm32_dma_write(dmadev, STM32_DMA_SM0AR(chan->id), reg->dma_sm0ar);
@@ -1343,6 +1344,7 @@ static int stm32_dma_probe(struct platform_device *pdev)
 	dd->directions = BIT(DMA_DEV_TO_MEM) | BIT(DMA_MEM_TO_DEV);
 	dd->residue_granularity = DMA_RESIDUE_GRANULARITY_BURST;
 	dd->max_burst = STM32_DMA_MAX_BURST;
+	dd->descriptor_reuse = true;
 	dd->dev = &pdev->dev;
 	INIT_LIST_HEAD(&dd->channels);