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| author | Sascha Hauer <s.hauer@pengutronix.de> | 2009-11-18 15:21:44 +0100 |
|---|---|---|
| committer | Sascha Hauer <s.hauer@pengutronix.de> | 2009-11-24 08:40:14 +0100 |
| commit | 4998f1a30cf8e21c5bc0766fde4fa58e1adabd72 (patch) | |
| tree | c58feecc32d7fbe7d128094a72ff9e4471fcdd3d /arch | |
| parent | 74b2a70e34c69687f82b1319a358b21afeea497c (diff) | |
| download | op-kernel-dev-4998f1a30cf8e21c5bc0766fde4fa58e1adabd72.zip op-kernel-dev-4998f1a30cf8e21c5bc0766fde4fa58e1adabd72.tar.gz | |
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: Sascha Hauer <s.hauer@pengutronix.de>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arm/plat-mxc/dma-mx1-mx2.c | 3 | ||||
| -rw-r--r-- | arch/arm/plat-mxc/include/mach/dma-mx1-mx2.h | 8 |
2 files changed, 10 insertions, 1 deletions
diff --git a/arch/arm/plat-mxc/dma-mx1-mx2.c b/arch/arm/plat-mxc/dma-mx1-mx2.c index 7764643..9c1b3f9 100644 --- a/arch/arm/plat-mxc/dma-mx1-mx2.c +++ b/arch/arm/plat-mxc/dma-mx1-mx2.c @@ -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)); diff --git a/arch/arm/plat-mxc/include/mach/dma-mx1-mx2.h b/arch/arm/plat-mxc/include/mach/dma-mx1-mx2.h index b3876cc..07be8ad 100644 --- a/arch/arm/plat-mxc/include/mach/dma-mx1-mx2.h +++ b/arch/arm/plat-mxc/include/mach/dma-mx1-mx2.h @@ -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, |
