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Subject[PATCH 17/17] ASoC: twl6040: Workaround for headset DC offset caused pop noise
Date
Both Headset DAC need to be enabled at the same time, before any of
the output drivers are enabled.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
---
include/linux/mfd/twl6040.h | 1 +
sound/soc/codecs/twl6040.c | 42 ++++++++++++++++++++++++++++++++++++++++--
2 files changed, 41 insertions(+), 2 deletions(-)
diff --git a/include/linux/mfd/twl6040.h b/include/linux/mfd/twl6040.h
index d9e05ea..0bbb1e7 100644
--- a/include/linux/mfd/twl6040.h
+++ b/include/linux/mfd/twl6040.h
@@ -122,6 +122,7 @@

/* HSLCTL/R (0x10/0x11) fields */

+#define TWL6040_HSDACENA (1 << 0)
#define TWL6040_HSDACMODE (1 << 1)
#define TWL6040_HSDRVMODE (1 << 3)

diff --git a/sound/soc/codecs/twl6040.c b/sound/soc/codecs/twl6040.c
index abde625..063defc 100644
--- a/sound/soc/codecs/twl6040.c
+++ b/sound/soc/codecs/twl6040.c
@@ -90,6 +90,7 @@ struct twl6040_data {
int pll_power_mode;
int hs_power_mode;
int hs_power_mode_locked;
+ int hs_dac_enabled;
unsigned int clk_in;
unsigned int sysclk;
u16 hs_left_step;
@@ -660,6 +661,43 @@ static int headset_power_mode(struct snd_soc_codec *codec, int high_perf)
static int twl6040_hs_dac_event(struct snd_soc_dapm_widget *w,
struct snd_kcontrol *kcontrol, int event)
{
+ struct snd_soc_codec *codec = w->codec;
+ struct twl6040_data *priv = snd_soc_codec_get_drvdata(codec);
+ u8 hslctl, hsrctl;
+
+ /*
+ * Workaround for Headset DC offset caused pop noise:
+ * Both HS DAC need to be turned on (before the HS driver) and off at
+ * the same time.
+ */
+ if (SND_SOC_DAPM_EVENT_ON(event)) {
+ if (!priv->hs_dac_enabled++) {
+ hslctl = twl6040_read_reg_cache(codec,
+ TWL6040_REG_HSLCTL);
+ hslctl |= TWL6040_HSDACENA;
+
+ hsrctl = twl6040_read_reg_cache(codec,
+ TWL6040_REG_HSRCTL);
+ hsrctl |= TWL6040_HSDACENA;
+
+ twl6040_write(codec, TWL6040_REG_HSLCTL, hslctl);
+ twl6040_write(codec, TWL6040_REG_HSRCTL, hsrctl);
+ }
+ } else {
+ if (!--priv->hs_dac_enabled) {
+ hslctl = twl6040_read_reg_cache(codec,
+ TWL6040_REG_HSLCTL);
+ hslctl &= ~TWL6040_HSDACENA;
+
+ hsrctl = twl6040_read_reg_cache(codec,
+ TWL6040_REG_HSRCTL);
+ hsrctl &= ~TWL6040_HSDACENA;
+
+ twl6040_write(codec, TWL6040_REG_HSLCTL, hslctl);
+ twl6040_write(codec, TWL6040_REG_HSRCTL, hsrctl);
+ }
+ }
+
msleep(1);
return 0;
}
@@ -1146,11 +1184,11 @@ static const struct snd_soc_dapm_widget twl6040_dapm_widgets[] = {

/* DACs */
SND_SOC_DAPM_DAC_E("HSDAC Left", "Headset Playback",
- TWL6040_REG_HSLCTL, 0, 0,
+ SND_SOC_NOPM, 0, 0,
twl6040_hs_dac_event,
SND_SOC_DAPM_POST_PMU | SND_SOC_DAPM_POST_PMD),
SND_SOC_DAPM_DAC_E("HSDAC Right", "Headset Playback",
- TWL6040_REG_HSRCTL, 0, 0,
+ SND_SOC_NOPM, 0, 0,
twl6040_hs_dac_event,
SND_SOC_DAPM_POST_PMU | SND_SOC_DAPM_POST_PMD),
SND_SOC_DAPM_DAC_E("HFDAC Left", "Handsfree Playback",
--
1.7.6.1


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