1 files changed, 22 insertions, 3 deletions

diff --git a/sound/soc/fsl/fsl_ssi.c b/sound/soc/fsl/fsl_ssi.c
index 7939c337ed9..d1c855ade8f 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";