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authorMaxime Ripard <maxime.ripard@free-electrons.com>2017-11-09 10:40:46 +0100
committerMark Brown <broonie@kernel.org>2017-11-09 11:41:51 +0000
commite7b8a6d3efa8316dfe786e9cd559c62e9152337c (patch)
treedb48e23875547a04e805680d91e4b2b0d219a3ab /sound/soc
parent18c1bf35c1c09bca05cf70bc984a4764e0b0372b (diff)
downloadlinux-e7b8a6d3efa8316dfe786e9cd559c62e9152337c.tar.bz2
ASoC: sun8i-codec: Add a comment on the LRCK inversion
The current code might be a bit intriguing without having experienced the issue before, and might come up as a mistake. Make explicit what's going on by adding a comment. Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com> Signed-off-by: Mark Brown <broonie@kernel.org>
Diffstat (limited to 'sound/soc')
-rw-r--r--sound/soc/sunxi/sun8i-codec.c11
1 files changed, 11 insertions, 0 deletions
diff --git a/sound/soc/sunxi/sun8i-codec.c b/sound/soc/sunxi/sun8i-codec.c
index c2ceca485d6a..b3329692e3dc 100644
--- a/sound/soc/sunxi/sun8i-codec.c
+++ b/sound/soc/sunxi/sun8i-codec.c
@@ -197,6 +197,17 @@ static int sun8i_set_fmt(struct snd_soc_dai *dai, unsigned int fmt)
regmap_update_bits(scodec->regmap, SUN8I_AIF1CLK_CTRL,
BIT(SUN8I_AIF1CLK_CTRL_AIF1_BCLK_INV),
value << SUN8I_AIF1CLK_CTRL_AIF1_BCLK_INV);
+
+ /*
+ * It appears that the DAI and the codec don't share the same
+ * polarity for the LRCK signal when they mean 'normal' and
+ * 'inverted' in the datasheet.
+ *
+ * Since the DAI here is our regular i2s driver that have been
+ * tested with way more codecs than just this one, it means
+ * that the codec probably gets it backward, and we have to
+ * invert the value here.
+ */
regmap_update_bits(scodec->regmap, SUN8I_AIF1CLK_CTRL,
BIT(SUN8I_AIF1CLK_CTRL_AIF1_LRCK_INV),
!value << SUN8I_AIF1CLK_CTRL_AIF1_LRCK_INV);