ASoC: wcd9310: Address pop noise at Tx path startup.
When microphone bias source turns on, the voltages on an electret
microphone does not immediately settle to a final voltage value.
Instead it takes 80-100ms (from empirical measurements) before the
microphone voltages finally settle. If the system receiveing this
voltage has a very low (high pass) corner frequency, the receiving
system will also have a very long settling time. In the case of an
ADC system, the system must stabilize to a value near 0 full-scale
before the stream is valid, otherwise a click will result in the
start of the file. To solve this problem and allow audio to stream
out of the digital CODEC without a click, a high pass filter with a
higher corner frequency is used for the time it takes for the
microphone voltages to finally stabilize.
Change-Id: Ib5986cb4c8694755da9c837d9575607e1126ec20
CRs-Fixed: 339929
Signed-off-by: Kiran Kandi <kkandi@codeaurora.org>
diff --git a/sound/soc/soc-dapm.c b/sound/soc/soc-dapm.c
index 3063f3e..265df9e 100644
--- a/sound/soc/soc-dapm.c
+++ b/sound/soc/soc-dapm.c
@@ -60,6 +60,7 @@
[snd_soc_dapm_pre] = 0,
[snd_soc_dapm_supply] = 1,
[snd_soc_dapm_micbias] = 2,
+ [snd_soc_dapm_adc] = 3,
[snd_soc_dapm_mic] = 4,
[snd_soc_dapm_mux] = 5,
[snd_soc_dapm_virt_mux] = 5,
@@ -70,7 +71,6 @@
[snd_soc_dapm_pga] = 8,
[snd_soc_dapm_aif_in] = 8,
[snd_soc_dapm_aif_out] = 8,
- [snd_soc_dapm_adc] = 9,
[snd_soc_dapm_out_drv] = 10,
[snd_soc_dapm_hp] = 10,
[snd_soc_dapm_spk] = 10,