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>

1 files changed, 8 insertions, 0 deletions

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 b3876cc238ca..07be8ad7ec37 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,