I just entered alsamixer command to watch and change some volumes, but I found there is too many playback controls!
Why there is so many??
Is there something on the driver that create virtual devices or controls?
It's a little difficult to figure out which one is Line out
A list of the playback/recording controls could be helpful. I see some are for EQ, other controls i have no idea.
This is the really short version...
The card has three analog inputs:
IN1R - Headset microphone. This is the right channel of analog input IN1. IN1L exists on the chip but isn't connected to anything.
IN2L and IN2R - The onboard DMIC microphones, left and right. Note that the markings on the board are wrong.
IN3L and IN3R - Line In, left and right.
There are two analog outputs:
HPOUT1L and HPOUT1R - Headset, left and right.
HPOUT2L and HPOUT2R - Line Out, left and right.
The card has three digital Audio InterFaces (AIF), each of which have a receiver (RX) and a transmitter (TX).
RX is signals coming in to the card from the Pi, the S/PDIF chip or the expansion connector. TX is signals going out from the card.
AIF1 - Interfaces with the Raspberry.
AIF2 - Interfaces with the S/PDIF chip.
AIF3 - For future goodies. On the expansion connector.
Speaker connections:
SPKOUTL and SPKOUTR - Onboard analog speaker circuit and amplifier.
SPKDATL and SPKDATR - Interface for Digital Speakers connected to the expansion connector.
Then there is a gazillion of other stuff on the card, equalizers, filters, DSPs and whatnot.
I'm working on writeup that will describe the card in more detail, but work and spending time with the family tends to get in the way. 
At least I have managed to make an illustration...
Anyhow, I hope this clears some of the fog
--
Ragnar
