On the other hand, the node of sysfs is quite common in Linux because it's tightly coupled to kernel objects. Let you see files under 'Documentation/ABI/'. We can find efforts to maintain sysfs node so safe and stable. Due to this reason, it's better to take more care when adding new node.
Would I request you the reason to add this node and the reason that current ALSA control interface doesn't satisfy your requirement?
simplicity for user support. Anyone can peak at a sysfs file, not everyone is familiar with the alsa control interface.
We get lots of bug reports from people who are asking for configuration help, and the simpler the command is the better.
For my information, would I request you to disclose the part of such reports?
I need supplemental information about the reason to add the alternative path to expose it, especially the reason that no developers work to improve existent tool relevant to UCM and are going to wish to add the alternative without utilizing ALSA control character device.
I don't understand your question, sorry. UCM already uses the control interface, it's not a matter of adding a new interface but making it easier to visualize the contents reported by the machine driver.
See for example https://github.com/alsa-project/alsa-ucm-conf/blob/4722f5b3859903521ba0f92a6...
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.
There is zero intent to advertise this sysfs node as a basis for applications to bypass the control interface, if that was what you thought I was promoting.