How to write a "config"?

[z3ntu]

Hello,
I didn't find it mentioned anywhere so how do I write the config that's being used in the -c parameter?
And also what to do with the resulting files (HiFi and a .conf file)?

EDIT: Just found the path /usr/share/alsa/ucm/.

[ford-prefect]

@z3ntu sorry about the sparse documentation -- the examples were meant to help get started. I wrote about some of the concepts and motivation at https://arunraghavan.net/2016/01/audio-devices-and-configuration/

I see you found where ALSA picks up UCM files from.

Feel free to ask more questions here.

[z3ntu]

As I never did anything with UCM/ALSA before, all the terms are pretty confusing (although I know the word "use case" in context of project management^^)

[z3ntu]

localhost:~# alsaucm -c msm8974-taiko-mtp-snd-card -i
ALSA lib main.c:438:(execute_sequence) unable to execute cset 'name='SLIMBUS_0_RX Port Mixer INT_BT_SCO_TX' 0'

ALSA lib main.c:536:(import_master_config) Unable to execute default sequence
ALSA lib main.c:946:(snd_use_case_mgr_open) error: failed to import msm8974-taiko-mtp-snd-card use case configuration -2
alsaucm: error failed to open sound card msm8974-taiko-mtp-snd-card: No such file or directory

After removing the line with SLIMBUS_0_RX Port Mixer INT_BT_SCO_TX and INTERNAL_BT_SCO_RX Audio Mixer Multimedia6 from my /usr/share/alsa/ucm/msm8974-taiko-mtp-snd-card/msm8974-taiko-mtp-snd-card.conf, I can finally launch alsaucm

(I began writing the above comment because I wanted help but apparently I managed to work around it myself)

Now aplay is still throwing errors: aplay: main:807: audio open error: Invalid argument. Any idea how I could find out why it's doing that? (maybe some magic command that tells me? ^^)

[ford-prefect]

Hmm, the invalid argument will need more looking at. See what parameters don't work. For the mixer controls, unfortunately, the set of mixer controls varies from kernel to kernel (I don't know if any of this is upstream), and probably based on the platform itself. When I wrote this, it was all done blind without access to any spec sheets. If you have these, it'll probably be a lot easier going.