[alsa-devel] [PATCH v3 1/3] ASoC: davinci-mcasp: Constraint on the period and buffer size based on FIFO usage

[Peter Ujfalusi]

We need to place constraint on the period if the read or write AFIFO
is enabled and it is configured for more than one word otherwise
the DMA will fail in buffer configuration where the sizes are not
aligned with the requested FIFO configuration.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi at ti.com>
---
 sound/soc/davinci/davinci-mcasp.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/sound/soc/davinci/davinci-mcasp.c b/sound/soc/davinci/davinci-mcasp.c
index a01ae97c90aa..df067a836c4d 100644
--- a/sound/soc/davinci/davinci-mcasp.c
+++ b/sound/soc/davinci/davinci-mcasp.c
@@ -720,6 +720,7 @@ static int davinci_mcasp_startup(struct snd_pcm_substream *substream,
 				 struct snd_soc_dai *dai)
 {
 	struct davinci_mcasp *mcasp = snd_soc_dai_get_drvdata(dai);
+	int afifo_numevt;
 
 	if (mcasp->version == MCASP_VERSION_4)
 		snd_soc_dai_set_dma_data(dai, substream,
@@ -727,6 +728,16 @@ static int davinci_mcasp_startup(struct snd_pcm_substream *substream,
 	else
 		snd_soc_dai_set_dma_data(dai, substream, mcasp->dma_params);
 
+	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
+		afifo_numevt = mcasp->txnumevt;
+	else
+		afifo_numevt = mcasp->rxnumevt;
+
+	if (afifo_numevt > 1)
+		snd_pcm_hw_constraint_step(substream->runtime, 0,
+					   SNDRV_PCM_HW_PARAM_PERIOD_SIZE,
+					   afifo_numevt);
+
 	return 0;
 }
 
-- 
1.9.0