Conexant Audio CX20641 driver for Win 10 64 bit - Inspiron 620

I've upgraded my Inspiron 620's OS to Win 10 a few months ago. There's no win 10 driver for its integrate audio (CX20641), so it keeps using the Win 7 driver from old OS.  

It works fine until recent days, the audio has a low probability that suddenly become no sound, if I click the "test" button it will pop up an alert "The device is being used by another application".

A simple restart can fix this problem, and the frequency of this problem is low - once per 2~3 days.

I've googled it and found out people solve it by upgrading audio driver, however for the audio I'm using, I can't find a proper driver for Win 10 (CX20641).

Thanks for your help!