[MinnowBoard] How to support RealTek ALC262 Codec Support connected to Intel HDA bus in MinnowBoard 0.82 firmware?

[Gerard Bucas]

Hi experts!

We have an Intel Atom Baytrail SoC (E3845) based board which has a Realtek
ALC262 audio codec connected to the Intel HDA bus. We used the 0.82
MinnowBoard MAX firmware as our starting "BIOS" and modified it to support
SODIMM's etc. We are using yocto built linux and Ubuntu as test OS's. Both
run well & are stable. HDA audio works (directed to HDMI).

However, our linux kernel does not "see/detect" the Realtek AudIo codec on
this board, whereas it does on other boards that have a similar setup using
a different BIOS. So I need some help with understanding how/what we need to
modify in the minnowMax firmware to support this ALC262 codec connected in
this way. 

I am a little confused as to what the BIOS/firmware does versus what the
linux kernel does to detect and initialize the device. I would have thought
that all detection and initialization of the ALC262 is done by the linux
kernel (assuming the correct drivers are included - which is the case) as
opposed to the (edk2/MinnowMAX based uefi firmware/BIOS)? So it seems I am
missing some fundamental concept in understanding "who does what" (firmware
versus OS kernel)?

Would really appreciate some input on this and some pointers as to how to
add the right support at the right level!

Thanks & Regards

Gerard