Commit 4998f1a3 authored by Sascha Hauer's avatar Sascha Hauer
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mxc: mx1/mx2 DMA: add a possibility to create an endless DMA transfer



This is useful for audio where we do not want to setup a new scatterlist
after playing 4GB of audio data. This would cause skips in the playback.
Signed-off-by: default avatarSascha Hauer <s.hauer@pengutronix.de>
parent 74b2a70e
......@@ -156,7 +156,8 @@ static inline int imx_dma_sg_next(int channel, struct scatterlist *sg)
}
now = min(imxdma->resbytes, sg->length);
imxdma->resbytes -= now;
if (imxdma->resbytes != IMX_DMA_LENGTH_LOOP)
imxdma->resbytes -= now;
if ((imxdma->dma_mode & DMA_MODE_MASK) == DMA_MODE_READ)
__raw_writel(sg->dma_address, DMA_BASE + DMA_DAR(channel));
......
......@@ -58,6 +58,14 @@ imx_dma_setup_single(int channel, dma_addr_t dma_address,
unsigned int dma_length, unsigned int dev_addr,
unsigned int dmamode);
/*
* Use this flag as the dma_length argument to imx_dma_setup_sg()
* to create an endless running dma loop. The end of the scatterlist
* must be linked to the beginning for this to work.
*/
#define IMX_DMA_LENGTH_LOOP ((unsigned int)-1)
int
imx_dma_setup_sg(int channel, struct scatterlist *sg,
unsigned int sgcount, unsigned int dma_length,
......
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