[alsa-devel] [PATCH v2 13/19] ASoC: tlv320aic31xx: Fix inverted BCLK handling

[Andrew F. Davis]

Currently BCLK inverting is only handled when the DAI format is
DSP, but the BCLK may be inverted in any supported mode. Without
this using this CODEC in any other mode than DSP with the BCLK
inverted leads to bad sampling timing and very poor audio quality.

Fixes: e00447fafbf7 ("ASoC: tlv320aic31xx: Add basic codec driver implementation")

Signed-off-by: Andrew F. Davis <afd at ti.com>
---
 sound/soc/codecs/tlv320aic31xx.c | 28 ++++++++++++++++++----------
 1 file changed, 18 insertions(+), 10 deletions(-)

diff --git a/sound/soc/codecs/tlv320aic31xx.c b/sound/soc/codecs/tlv320aic31xx.c
index b39db3eb06d0..f7b1ec96d826 100644
--- a/sound/soc/codecs/tlv320aic31xx.c
+++ b/sound/soc/codecs/tlv320aic31xx.c
@@ -939,6 +939,18 @@ static int aic31xx_set_dai_fmt(struct snd_soc_dai *codec_dai,
 		return -EINVAL;
 	}
 
+	/* signal polarity */
+	switch (fmt & SND_SOC_DAIFMT_INV_MASK) {
+	case SND_SOC_DAIFMT_NB_NF:
+		break;
+	case SND_SOC_DAIFMT_IB_NF:
+		iface_reg2 |= AIC31XX_BCLKINV_MASK;
+		break;
+	default:
+		dev_err(codec->dev, "Invalid DAI clock signal polarity\n");
+		return -EINVAL;
+	}
+
 	/* interface format */
 	switch (fmt & SND_SOC_DAIFMT_FORMAT_MASK) {
 	case SND_SOC_DAIFMT_I2S:
@@ -946,16 +958,12 @@ static int aic31xx_set_dai_fmt(struct snd_soc_dai *codec_dai,
 	case SND_SOC_DAIFMT_DSP_A:
 		dsp_a_val = 0x1; /* fall through */
 	case SND_SOC_DAIFMT_DSP_B:
-		/* NOTE: BCLKINV bit value 1 equas NB and 0 equals IB */
-		switch (fmt & SND_SOC_DAIFMT_INV_MASK) {
-		case SND_SOC_DAIFMT_NB_NF:
-			iface_reg2 |= AIC31XX_BCLKINV_MASK;
-			break;
-		case SND_SOC_DAIFMT_IB_NF:
-			break;
-		default:
-			return -EINVAL;
-		}
+		/*
+		 * NOTE: This CODEC samples on the falling edge of BCLK in
+		 * DSP mode, this is inverted compared to what most DAIs
+		 * expect, so we invert for this mode
+		 */
+		iface_reg2 ^= AIC31XX_BCLKINV_MASK;
 		iface_reg1 |= (AIC31XX_DSP_MODE <<
 			       AIC31XX_IFACE1_DATATYPE_SHIFT);
 		break;
-- 
2.15.0