alsa-project alsa-ucm : Audio endpoint is not switching when external mic connected

[Mukunda, Vijendar]

We recently up streamed ACP PDM driver for Renoir APU.

Our ACP IP has an internal PDM Decoder block where DMIC is directly connected.
There are no KControls defined for PDM Driver.

Our platform supports on board DMIC and South bridge Azalia (HD Audio ) endpoint .
By default, DMIC endpoint is used as audio input device.
When Headset Mic jack connected, it's not switching to External Mic.

How does audio endpoint will switch in gnome when external mic is connected?
>From our understanding, UCM conf file for HDA driver is also required for 
configuring mixer controls for HD Audio capture device.
Similarly when External Mic is removed , it has to switch to internal dmic .

Need help in resolving this issue.

Thanks,
Vijendar