[PATCH] ALSA: core: sysfs: show components string

[Pierre-Louis Bossart]

>>> 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/4722f5b3859903521ba0f92a64d86af31083ca50/ucm2/sof-hda-dsp/HiFi.conf#L145

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.