[PATCH V2] ASoC: fsl_asrc: add constraint for the asrc of older version

[S.j. Wang]

There is constraint for the channel number setting on the
asrc of older version (e.g. imx35), the channel number should
be even, odd number isn't valid.

So add this constraint when the asrc of older version is used.

Signed-off-by: Shengjiu Wang <shengjiu.wang at nxp.com>
---
changes in v2
- switch to add constraint in startup function

 sound/soc/fsl/fsl_asrc.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/sound/soc/fsl/fsl_asrc.c b/sound/soc/fsl/fsl_asrc.c
index 528e8b108422..31494f225037 100644
--- a/sound/soc/fsl/fsl_asrc.c
+++ b/sound/soc/fsl/fsl_asrc.c
@@ -445,6 +445,19 @@ struct dma_chan *fsl_asrc_get_dma_channel(struct fsl_asrc_pair *pair, bool dir)
 }
 EXPORT_SYMBOL_GPL(fsl_asrc_get_dma_channel);
 
+static int fsl_asrc_dai_startup(struct snd_pcm_substream *substream,
+				struct snd_soc_dai *dai)
+{
+	struct fsl_asrc *asrc_priv = snd_soc_dai_get_drvdata(dai);
+
+	/* channel_bits = 3 means older version on imx35*/
+	if (asrc_priv->channel_bits == 3)
+		snd_pcm_hw_constraint_step(substream->runtime, 0,
+					   SNDRV_PCM_HW_PARAM_CHANNELS, 2);
+
+	return 0;
+}
+
 static int fsl_asrc_dai_hw_params(struct snd_pcm_substream *substream,
 				  struct snd_pcm_hw_params *params,
 				  struct snd_soc_dai *dai)
@@ -539,6 +552,7 @@ static int fsl_asrc_dai_trigger(struct snd_pcm_substream *substream, int cmd,
 }
 
 static const struct snd_soc_dai_ops fsl_asrc_dai_ops = {
+	.startup      = fsl_asrc_dai_startup,
 	.hw_params    = fsl_asrc_dai_hw_params,
 	.hw_free      = fsl_asrc_dai_hw_free,
 	.trigger      = fsl_asrc_dai_trigger,
-- 
1.9.1