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dma: edma: Increase maximum SG limit to 20

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davinci-pcm uses 16 as the no.of periods. With this, in EDMA we have to
allocate atleast 17 slots: 1 slot for channel, and 16 slots the periods.

Due to this, the MAX_NR_SG limitation causes problems, set it to 20 to make
cyclic DMA work when davinci-pcm is converted to use DMA Engine. Also add
a comment clarifying this.

Signed-off-by: Joel Fernandes <joelf@ti.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
This commit is contained in:
Joel Fernandes 2013-09-23 18:05:15 -05:00 committed by Vinod Koul
parent fd00903504
commit 2abd5f1b97
1 changed files with 8 additions and 2 deletions
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10
drivers/dma/edma.c
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@ -46,8 +46,14 @@
#define EDMA_CHANS 64
#endif /* CONFIG_ARCH_DAVINCI_DA8XX */
/* Max of 16 segments per channel to conserve PaRAM slots */
#define MAX_NR_SG 16
/*
* Max of 20 segments per channel to conserve PaRAM slots
* Also note that MAX_NR_SG should be atleast the no.of periods
* that are required for ASoC, otherwise DMA prep calls will
* fail. Today davinci-pcm is the only user of this driver and
* requires atleast 17 slots, so we setup the default to 20.
*/
#define MAX_NR_SG 20
#define EDMA_MAX_SLOTS MAX_NR_SG
#define EDMA_DESCRIPTORS 16