[PATCH v2 1/2] ASoC: sophgo: cv1800b: document DAC overwrite handling

[Anton D. Stavinskii]

Add comments to cv1800b_dac_mute() and its caller to explain how the
overwrite mechanism works and why we force it off before playback.

Signed-off-by: Anton D. Stavinskii <stavinsky at gmail.com>
---
 sound/soc/sophgo/cv1800b-sound-dac.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/sound/soc/sophgo/cv1800b-sound-dac.c b/sound/soc/sophgo/cv1800b-sound-dac.c
index ccf386174639..135322bcf6ad 100644
--- a/sound/soc/sophgo/cv1800b-sound-dac.c
+++ b/sound/soc/sophgo/cv1800b-sound-dac.c
@@ -57,6 +57,10 @@ static void cv1800b_dac_enable(struct cv1800b_priv *priv, bool enable)
 	writel(val, priv->regs + CV1800B_TXDAC_CTRL0);
 }
 
+/*
+ * Control the DAC overwrite bits. When enabled, the DAC outputs the fixed
+ * overwrite value instead of samples from the I2S input.
+ */
 static void cv1800b_dac_mute(struct cv1800b_priv *priv, bool enable)
 {
 	u32 val;
@@ -105,7 +109,7 @@ static int cv1800b_dac_hw_params(struct snd_pcm_substream *substream,
 		dev_err(priv->dev, "rate %u is not supported\n", rate);
 		return -EINVAL;
 	}
-
+	/* Clear DAC overwrite so playback uses I2S data. */
 	cv1800b_dac_mute(priv, false);
 	/* minimal decimation for 48kHz is 64*/
 	ret = cv1800b_dac_decimation(priv, DECIMATION_64);

-- 
2.43.0