[alsa-devel] [PATCH v5 01/15] ASoC: sun4i-i2s: Add regmap field to sign extend sample

[codekipper at gmail.com]

From: Marcus Cooper <codekipper at gmail.com>

On the newer SoCs such as the H3 and A64 this is set by default
to transfer a 0 after each sample in each slot. However the A10
and A20 SoCs that this driver was developed on had a default
setting where it padded the audio gain with zeros.

This isn't a problem whilst we have only support for 16bit audio
but with larger sample resolution rates in the pipeline then SEXT
bits should be cleared so that they also pad at the LSB. Without
this the audio gets distorted.

Signed-off-by: Marcus Cooper <codekipper at gmail.com>
---
 sound/soc/sunxi/sun4i-i2s.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/sound/soc/sunxi/sun4i-i2s.c b/sound/soc/sunxi/sun4i-i2s.c
index 793457394efe..8201334a059b 100644
--- a/sound/soc/sunxi/sun4i-i2s.c
+++ b/sound/soc/sunxi/sun4i-i2s.c
@@ -135,6 +135,7 @@ struct sun4i_i2s;
  * @field_fmt_bclk: regmap field to set clk polarity.
  * @field_fmt_lrclk: regmap field to set frame polarity.
  * @field_fmt_mode: regmap field to set the operational mode.
+ * @field_fmt_sext: regmap field to set the sign extension.
  * @field_txchanmap: location of the tx channel mapping register.
  * @field_rxchanmap: location of the rx channel mapping register.
  * @field_txchansel: location of the tx channel select bit fields.
@@ -159,6 +160,7 @@ struct sun4i_i2s_quirks {
 	struct reg_field		field_fmt_bclk;
 	struct reg_field		field_fmt_lrclk;
 	struct reg_field		field_fmt_mode;
+	struct reg_field		field_fmt_sext;
 	struct reg_field		field_txchanmap;
 	struct reg_field		field_rxchanmap;
 	struct reg_field		field_txchansel;
@@ -186,6 +188,7 @@ struct sun4i_i2s {
 	struct regmap_field	*field_fmt_bclk;
 	struct regmap_field	*field_fmt_lrclk;
 	struct regmap_field	*field_fmt_mode;
+	struct regmap_field	*field_fmt_sext;
 	struct regmap_field	*field_txchanmap;
 	struct regmap_field	*field_rxchanmap;
 	struct regmap_field	*field_txchansel;
@@ -345,6 +348,9 @@ static int sun4i_i2s_set_clk_rate(struct snd_soc_dai *dai,
 				   SUN8I_I2S_FMT0_LRCK_PERIOD_MASK,
 				   SUN8I_I2S_FMT0_LRCK_PERIOD(32));
 
+	/* Set sign extension to pad out LSB with 0 */
+	regmap_field_write(i2s->field_fmt_sext, 0);
+
 	return 0;
 }
 
@@ -917,6 +923,7 @@ static const struct sun4i_i2s_quirks sun4i_a10_i2s_quirks = {
 	.field_fmt_lrclk	= REG_FIELD(SUN4I_I2S_FMT0_REG, 7, 7),
 	.has_slave_select_bit	= true,
 	.field_fmt_mode		= REG_FIELD(SUN4I_I2S_FMT0_REG, 0, 1),
+	.field_fmt_sext		= REG_FIELD(SUN4I_I2S_FMT1_REG, 8, 8),
 	.field_txchanmap	= REG_FIELD(SUN4I_I2S_TX_CHAN_MAP_REG, 0, 31),
 	.field_rxchanmap	= REG_FIELD(SUN4I_I2S_RX_CHAN_MAP_REG, 0, 31),
 	.field_txchansel	= REG_FIELD(SUN4I_I2S_TX_CHAN_SEL_REG, 0, 2),
@@ -936,6 +943,7 @@ static const struct sun4i_i2s_quirks sun6i_a31_i2s_quirks = {
 	.field_fmt_lrclk	= REG_FIELD(SUN4I_I2S_FMT0_REG, 7, 7),
 	.has_slave_select_bit	= true,
 	.field_fmt_mode		= REG_FIELD(SUN4I_I2S_FMT0_REG, 0, 1),
+	.field_fmt_sext		= REG_FIELD(SUN4I_I2S_FMT1_REG, 8, 8),
 	.field_txchanmap	= REG_FIELD(SUN4I_I2S_TX_CHAN_MAP_REG, 0, 31),
 	.field_rxchanmap	= REG_FIELD(SUN4I_I2S_RX_CHAN_MAP_REG, 0, 31),
 	.field_txchansel	= REG_FIELD(SUN4I_I2S_TX_CHAN_SEL_REG, 0, 2),
@@ -979,6 +987,7 @@ static const struct sun4i_i2s_quirks sun8i_h3_i2s_quirks = {
 	.field_fmt_bclk		= REG_FIELD(SUN4I_I2S_FMT0_REG, 7, 7),
 	.field_fmt_lrclk	= REG_FIELD(SUN4I_I2S_FMT0_REG, 19, 19),
 	.field_fmt_mode		= REG_FIELD(SUN4I_I2S_CTRL_REG, 4, 5),
+	.field_fmt_sext		= REG_FIELD(SUN4I_I2S_FMT1_REG, 4, 5),
 	.field_txchanmap	= REG_FIELD(SUN8I_I2S_TX_CHAN_MAP_REG, 0, 31),
 	.field_rxchanmap	= REG_FIELD(SUN8I_I2S_RX_CHAN_MAP_REG, 0, 31),
 	.field_txchansel	= REG_FIELD(SUN8I_I2S_TX_CHAN_SEL_REG, 0, 2),
@@ -998,6 +1007,7 @@ static const struct sun4i_i2s_quirks sun50i_a64_codec_i2s_quirks = {
 	.field_fmt_bclk		= REG_FIELD(SUN4I_I2S_FMT0_REG, 6, 6),
 	.field_fmt_lrclk	= REG_FIELD(SUN4I_I2S_FMT0_REG, 7, 7),
 	.field_fmt_mode		= REG_FIELD(SUN4I_I2S_FMT0_REG, 0, 1),
+	.field_fmt_sext		= REG_FIELD(SUN4I_I2S_FMT1_REG, 8, 8),
 	.field_txchanmap	= REG_FIELD(SUN4I_I2S_TX_CHAN_MAP_REG, 0, 31),
 	.field_rxchanmap	= REG_FIELD(SUN4I_I2S_RX_CHAN_MAP_REG, 0, 31),
 	.field_txchansel	= REG_FIELD(SUN4I_I2S_TX_CHAN_SEL_REG, 0, 2),
@@ -1045,6 +1055,12 @@ static int sun4i_i2s_init_regmap_fields(struct device *dev,
 	if (IS_ERR(i2s->field_fmt_mode))
 		return PTR_ERR(i2s->field_fmt_mode);
 
+	i2s->field_fmt_sext =
+			devm_regmap_field_alloc(dev, i2s->regmap,
+						i2s->variant->field_fmt_sext);
+	if (IS_ERR(i2s->field_fmt_sext))
+		return PTR_ERR(i2s->field_fmt_sext);
+
 	i2s->field_txchanmap =
 			devm_regmap_field_alloc(dev, i2s->regmap,
 						i2s->variant->field_txchanmap);
-- 
2.22.0