To reduce pop noise during playback stream start and stop the codec needs to have the digital_mute callback implemented. The codec need to be muted before the CPU dai has been stopped (McPDM). Stopping the McPDM will generate a pop on the codec since no signal on the PDM bus means full negative amplitude. By managing the mute/unmute state of the outputs we can decrease the amount of pop noise when playback starts or stops.
Signed-off-by: Peter Ujfalusi peter.ujfalusi@ti.com --- sound/soc/codecs/twl6040.c | 91 +++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 90 insertions(+), 1 deletion(-)
diff --git a/sound/soc/codecs/twl6040.c b/sound/soc/codecs/twl6040.c index 9ea3dbc..44621dd 100644 --- a/sound/soc/codecs/twl6040.c +++ b/sound/soc/codecs/twl6040.c @@ -75,6 +75,8 @@ struct twl6040_data { int pll_power_mode; int hs_power_mode; int hs_power_mode_locked; + bool dl1_unmuted; + bool dl2_unmuted; unsigned int clk_in; unsigned int sysclk; struct twl6040_jack_data hs_jack; @@ -228,6 +230,25 @@ static int twl6040_read_reg_volatile(struct snd_soc_codec *codec, return value; }
+static bool twl6040_is_path_unmuted(struct snd_soc_codec *codec, + unsigned int reg) +{ + struct twl6040_data *priv = snd_soc_codec_get_drvdata(codec); + + switch (reg) { + case TWL6040_REG_HSLCTL: + case TWL6040_REG_HSRCTL: + case TWL6040_REG_EARCTL: + /* DL1 path */ + return priv->dl1_unmuted; + case TWL6040_REG_HFLCTL: + case TWL6040_REG_HFRCTL: + return priv->dl2_unmuted; + default: + return 1; + }; +} + /* * write to the twl6040 register space */ @@ -240,7 +261,8 @@ static int twl6040_write(struct snd_soc_codec *codec, return -EIO;
twl6040_write_reg_cache(codec, reg, value); - if (likely(reg < TWL6040_REG_SW_SHADOW)) + if (likely(reg < TWL6040_REG_SW_SHADOW) && + twl6040_is_path_unmuted(codec, reg)) return twl6040_reg_write(twl6040, reg, value); else return 0; @@ -1034,11 +1056,78 @@ static int twl6040_set_dai_sysclk(struct snd_soc_dai *codec_dai, return 0; }
+static void twl6040_mute_path(struct snd_soc_codec *codec, enum twl6040_dai_id id, + int mute) +{ + struct twl6040 *twl6040 = codec->control_data; + struct twl6040_data *priv = snd_soc_codec_get_drvdata(codec); + int hslctl, hsrctl, earctl; + int hflctl, hfrctl; + + switch (id) { + case TWL6040_DAI_DL1: + hslctl = twl6040_read_reg_cache(codec, TWL6040_REG_HSLCTL); + hsrctl = twl6040_read_reg_cache(codec, TWL6040_REG_HSRCTL); + earctl = twl6040_read_reg_cache(codec, TWL6040_REG_EARCTL); + + if (mute) { + /* Power down drivers and DACs */ + earctl &= ~0x01; + hslctl &= ~(TWL6040_HSDRVENA | TWL6040_HSDACENA); + hsrctl &= ~(TWL6040_HSDRVENA | TWL6040_HSDACENA); + + } + + twl6040_reg_write(twl6040, TWL6040_REG_EARCTL, earctl); + twl6040_reg_write(twl6040, TWL6040_REG_HSLCTL, hslctl); + twl6040_reg_write(twl6040, TWL6040_REG_HSRCTL, hsrctl); + priv->dl1_unmuted = !mute; + break; + case TWL6040_DAI_DL2: + hflctl = twl6040_read_reg_cache(codec, TWL6040_REG_HFLCTL); + hfrctl = twl6040_read_reg_cache(codec, TWL6040_REG_HFRCTL); + + if (mute) { + /* Power down drivers and DACs */ + hflctl &= ~(TWL6040_HFDACENA | TWL6040_HFPGAENA | + TWL6040_HFDRVENA); + hfrctl &= ~(TWL6040_HFDACENA | TWL6040_HFPGAENA | + TWL6040_HFDRVENA); + } + + twl6040_reg_write(twl6040, TWL6040_REG_HFLCTL, hflctl); + twl6040_reg_write(twl6040, TWL6040_REG_HFRCTL, hfrctl); + priv->dl2_unmuted = !mute; + break; + default: + break; + }; +} + +static int twl6040_digital_mute(struct snd_soc_dai *dai, int mute) +{ + switch (dai->id) { + case TWL6040_DAI_LEGACY: + twl6040_mute_path(dai->codec, TWL6040_DAI_DL1, mute); + twl6040_mute_path(dai->codec, TWL6040_DAI_DL2, mute); + break; + case TWL6040_DAI_DL1: + case TWL6040_DAI_DL2: + twl6040_mute_path(dai->codec, dai->id, mute); + break; + default: + break; + } + + return 0; +} + static const struct snd_soc_dai_ops twl6040_dai_ops = { .startup = twl6040_startup, .hw_params = twl6040_hw_params, .prepare = twl6040_prepare, .set_sysclk = twl6040_set_dai_sysclk, + .digital_mute = twl6040_digital_mute, };
static struct snd_soc_dai_driver twl6040_dai[] = {