diff options
Diffstat (limited to 'sound/soc/fsl/fsl_ssi.c')
| -rw-r--r-- | sound/soc/fsl/fsl_ssi.c | 25 |
1 files changed, 22 insertions, 3 deletions
diff --git a/sound/soc/fsl/fsl_ssi.c b/sound/soc/fsl/fsl_ssi.c index 7939c337ed9d..d1c855ade8fb 100644 --- a/sound/soc/fsl/fsl_ssi.c +++ b/sound/soc/fsl/fsl_ssi.c @@ -93,6 +93,7 @@ struct fsl_ssi_private { unsigned int playback; unsigned int capture; int asynchronous; + unsigned int fifo_depth; struct snd_soc_dai_driver cpu_dai_drv; struct device_attribute dev_attr; struct platform_device *pdev; @@ -337,11 +338,20 @@ static int fsl_ssi_startup(struct snd_pcm_substream *substream, /* * Set the watermark for transmit FIFI 0 and receive FIFO 0. We - * don't use FIFO 1. Since the SSI only supports stereo, the - * watermark should never be an odd number. + * don't use FIFO 1. We program the transmit water to signal a + * DMA transfer if there are only two (or fewer) elements left + * in the FIFO. Two elements equals one frame (left channel, + * right channel). This value, however, depends on the depth of + * the transmit buffer. + * + * We program the receive FIFO to notify us if at least two + * elements (one frame) have been written to the FIFO. We could + * make this value larger (and maybe we should), but this way + * data will be written to memory as soon as it's available. */ out_be32(&ssi->sfcsr, - CCSR_SSI_SFCSR_TFWM0(6) | CCSR_SSI_SFCSR_RFWM0(2)); + CCSR_SSI_SFCSR_TFWM0(ssi_private->fifo_depth - 2) | + CCSR_SSI_SFCSR_RFWM0(ssi_private->fifo_depth - 2)); /* * We keep the SSI disabled because if we enable it, then the @@ -622,6 +632,7 @@ static int __devinit fsl_ssi_probe(struct of_device *of_dev, struct device_attribute *dev_attr = NULL; struct device_node *np = of_dev->dev.of_node; const char *p, *sprop; + const uint32_t *iprop; struct resource res; char name[64]; @@ -678,6 +689,14 @@ static int __devinit fsl_ssi_probe(struct of_device *of_dev, else ssi_private->cpu_dai_drv.symmetric_rates = 1; + /* Determine the FIFO depth. */ + iprop = of_get_property(np, "fsl,fifo-depth", NULL); + if (iprop) + ssi_private->fifo_depth = *iprop; + else + /* Older 8610 DTs didn't have the fifo-depth property */ + ssi_private->fifo_depth = 8; + /* Initialize the the device_attribute structure */ dev_attr = &ssi_private->dev_attr; dev_attr->attr.name = "statistics"; |