ASoC: da7219: Add delays to capture path to remove DC offset noise

On some platforms it has been noted that a pop noise can be
witnessed when capturing audio, mainly for first time after a
headset jack has been inserted. This is due to a DC offset in the
Mic PGA and so to avoid this delays are required when powering
up the capture path.

This commit rectifies the problem by adding delays post Mic PGA and
post Mixin PGA. The post Mic PGA delay is determined based on
Mic Bias voltage, and is only applied the first time after a
headset jack is inserted.

Signed-off-by: Adam Thomson <Adam.Thomson.Opensource@diasemi.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 38 insertions, 6 deletions

diff --git a/sound/soc/codecs/da7219.c b/sound/soc/codecs/da7219.c
index c0144f2f8174..e46e9f4bc994 100644
--- a/sound/soc/codecs/da7219.c
+++ b/sound/soc/codecs/da7219.c
@@ -768,6 +768,30 @@ static const struct snd_kcontrol_new da7219_st_out_filtr_mix_controls[] = {
  * DAPM Events
  */
 
+static int da7219_mic_pga_event(struct snd_soc_dapm_widget *w,
+				struct snd_kcontrol *kcontrol, int event)
+{
+	struct snd_soc_component *component = snd_soc_dapm_to_component(w->dapm);
+	struct da7219_priv *da7219 = snd_soc_component_get_drvdata(component);
+
+	switch (event) {
+	case SND_SOC_DAPM_POST_PMU:
+		if (da7219->micbias_on_event) {
+			/*
+			 * Delay only for first capture after bias enabled to
+			 * avoid possible DC offset related noise.
+			 */
+			da7219->micbias_on_event = false;
+			msleep(da7219->mic_pga_delay);
+		}
+		break;
+	default:
+		break;
+	}
+
+	return 0;
+}
+
 static int da7219_dai_event(struct snd_soc_dapm_widget *w,
 			    struct snd_kcontrol *kcontrol, int event)
 {
@@ -937,12 +961,12 @@ static const struct snd_soc_dapm_widget da7219_dapm_widgets[] = {
 	SND_SOC_DAPM_INPUT("MIC"),
 
 	/* Input PGAs */
-	SND_SOC_DAPM_PGA("Mic PGA", DA7219_MIC_1_CTRL,
-			 DA7219_MIC_1_AMP_EN_SHIFT, DA7219_NO_INVERT,
-			 NULL, 0),
-	SND_SOC_DAPM_PGA("Mixin PGA", DA7219_MIXIN_L_CTRL,
-			 DA7219_MIXIN_L_AMP_EN_SHIFT, DA7219_NO_INVERT,
-			 NULL, 0),
+	SND_SOC_DAPM_PGA_E("Mic PGA", DA7219_MIC_1_CTRL,
+			   DA7219_MIC_1_AMP_EN_SHIFT, DA7219_NO_INVERT,
+			   NULL, 0, da7219_mic_pga_event, SND_SOC_DAPM_POST_PMU),
+	SND_SOC_DAPM_PGA_E("Mixin PGA", DA7219_MIXIN_L_CTRL,
+			   DA7219_MIXIN_L_AMP_EN_SHIFT, DA7219_NO_INVERT,
+			   NULL, 0, da7219_settling_event, SND_SOC_DAPM_POST_PMU),
 
 	/* Input Filters */
 	SND_SOC_DAPM_ADC("ADC", NULL, DA7219_ADC_L_CTRL, DA7219_ADC_L_EN_SHIFT,
@@ -1847,6 +1871,14 @@ static void da7219_handle_pdata(struct snd_soc_component *component)
 
 		snd_soc_component_write(component, DA7219_MICBIAS_CTRL, micbias_lvl);
 
+		/*
+		 * Calculate delay required to compensate for DC offset in
+		 * Mic PGA, based on Mic Bias voltage.
+		 */
+		da7219->mic_pga_delay =  DA7219_MIC_PGA_BASE_DELAY +
+					(pdata->micbias_lvl *
+					 DA7219_MIC_PGA_OFFSET_DELAY);
+
 		/* Mic */
 		switch (pdata->mic_amp_in_sel) {
 		case DA7219_MIC_AMP_IN_SEL_DIFF: