when people report that their microphone is not reported by PulseAudio/UCM, it's very helpful to know what UCM was supposed to use in the first place. We don't have a debugger or step-by-step mechanisms to figure out what the configurations are.
If I get your intension correctly, the addition of sysfs node is just to investigate which use-case configuration is applied in cases that people get issues. If so, it's really exaggerative in a point of the concept of sysfs.
I have two alternatives. If it's possible to focus on ALSA SoC part only, addition of node to debugfs is reasonable for this purpose.
Another alternative is to change output of 'cards' node of procfs. The latter is commonly available for all cases. For example:
I initially wanted to use /proc but thought it was a thing from the past so I looked at sysfs. If this is the recommendation I don't mind using it.
procfs will practically never die, and it's already there, so I'm fine with that path, too, supposing that the primary purpose is for help debugging / analyzing. If it's used by UCM or whatever configuration tool, sysfs is the better choice, OTOH.
debugsfs is not something the average user is familiar with, and it's not available in all cases. I'd like to extend existing pieces of information than add new things.
Right, debugfs isn't available per card as default, so it's no good option.
ok, let's go with procfs then, thanks for the feedback. I'll work on an update and resubmit. -Pierre