Need Help With VIA VT2021 Codec

[nittin]

I tried to make VIA VT2021 audio codec work with AppleHDA. So far it was a success, but not 100%. I managed to get the below ports working properly

 

1. Rear Green (EAPD is present) – IntSpeaker

2. Rear Blue – LineIn

3. Rear SPDIF Out

4. Front Green - Headphone

 

But hit a barrier with “Front & Rear Microphones” working only as “LineIn”. Yet it shows as Internal Microphone in System preferences. (only works as “internal mic”, not “ExtMic”)

 

After few days of investigation, I figured out the reason, why it’s only working as LineIn. By default the power ports (VREF ports) are off for both front and rear microphones. Look at the functional diagram VIA VT2021 DOCUMENTATION COPY

 

 

 

Pin 28 (VrefOut-B-L) & 32 (VrefOut-B-R) power the Rear Mic “21/22 Port B”.

Pin 30 (VrefOut-F) powers Front Mic “16/17 Port F”

 

Note – Pin 16, 17, 21, 22, 28, 30 are not Node ID’s. It’s the sequential pin numbers in circuit

 

You can see (highlighted in red) the VREF ports are off by default and we need to trigger these “VREF switches” in order to get front & rear Mic working as microphones

 

I’ve done lot of researches online, but couldn’t get any clue on “how to trigger these ports”.

 

Can you shed some light on how to trigger these ports? I’d really appreciate if you can help on this matter. I’ve attached all inputs for this project below

 

Thanks in advance