[PATCH v2 2/5] soundwire: intel: add prepare support in sdw dai driver

[Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>]

From: Rander Wang <rander.wang@linux.intel.com>

The existing code does not expose a prepare operation, which is very
much needed to deal with underflow and resume operations.

Signed-off-by: Rander Wang <rander.wang@linux.intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
---
 drivers/soundwire/intel.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/drivers/soundwire/intel.c b/drivers/soundwire/intel.c
index 78b2ebf0119c..bad7c30f1e01 100644
--- a/drivers/soundwire/intel.c
+++ b/drivers/soundwire/intel.c
@@ -699,6 +699,21 @@ static int intel_hw_params(struct snd_pcm_substream *substream,
 	return ret;
 }
 
+static int intel_prepare(struct snd_pcm_substream *substream,
+			 struct snd_soc_dai *dai)
+{
+	struct sdw_cdns_dma_data *dma;
+
+	dma = snd_soc_dai_get_dma_data(dai, substream);
+	if (!dma) {
+		dev_err(dai->dev, "failed to get dma data in %s",
+			__func__);
+		return -EIO;
+	}
+
+	return sdw_prepare_stream(dma->stream);
+}
+
 static int
 intel_hw_free(struct snd_pcm_substream *substream, struct snd_soc_dai *dai)
 {
@@ -745,6 +760,7 @@ static int intel_pdm_set_sdw_stream(struct snd_soc_dai *dai,
 
 static const struct snd_soc_dai_ops intel_pcm_dai_ops = {
 	.hw_params = intel_hw_params,
+	.prepare = intel_prepare,
 	.hw_free = intel_hw_free,
 	.shutdown = intel_shutdown,
 	.set_sdw_stream = intel_pcm_set_sdw_stream,
@@ -752,6 +768,7 @@ static const struct snd_soc_dai_ops intel_pcm_dai_ops = {
 
 static const struct snd_soc_dai_ops intel_pdm_dai_ops = {
 	.hw_params = intel_hw_params,
+	.prepare = intel_prepare,
 	.hw_free = intel_hw_free,
 	.shutdown = intel_shutdown,
 	.set_sdw_stream = intel_pdm_set_sdw_stream,
-- 
2.20.1