[PATCH] ASoC: only first codec is master in multicodec setup

[PATCH] ASoC: only first codec is master in multicodec setup

[Johannes Krude]

When using multiple codecs, at most one codec should generate the master
clock. All codecs except the first are therefore configured for slave
mode.

Signed-off-by: Johannes Krude <johannes@krude.de>
---
 sound/soc/soc-core.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/sound/soc/soc-core.c b/sound/soc/soc-core.c
index e697258d2..13a7d5b52 100644
--- a/sound/soc/soc-core.c
+++ b/sound/soc/soc-core.c
@@ -1417,7 +1417,15 @@ int snd_soc_runtime_set_dai_fmt(struct snd_soc_pcm_runtime *rtd,
 	int ret;
 
 	for_each_rtd_codec_dais(rtd, i, codec_dai) {
-		ret = snd_soc_dai_set_fmt(codec_dai, dai_fmt);
+		unsigned int codec_dai_fmt = dai_fmt;
+
+		// there can only be one master when using multiple codecs
+		if (i && (codec_dai_fmt & SND_SOC_DAIFMT_MASTER_MASK)) {
+			codec_dai_fmt &= ~SND_SOC_DAIFMT_MASTER_MASK;
+			codec_dai_fmt |= SND_SOC_DAIFMT_CBS_CFS;
+		}
+
+		ret = snd_soc_dai_set_fmt(codec_dai, codec_dai_fmt);
 		if (ret != 0 && ret != -ENOTSUPP) {
 			dev_warn(codec_dai->dev,
 				 "ASoC: Failed to set DAI format: %d\n", ret);
-- 
2.25.1