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>
2 files changed