Hi Morimoto-san,
...
If we encode use case information in DT, it would become regid and is not flexible when the HW is giving us the all flexibility (at least in my case). Thus may lead to complications. If there is a way to configure PCM parameters from the user space it would help to simplify things. Then DT can just describe the HW links.
What kind of PCM parameters you want to get from user-space ?
I was referring to channels, rate, sample size for PCM parameters which are part of hw_params(). Having these strictly defined in DT would limit from using the same audio path for different configurations. So far used mixer controls for overriding this info in hw_param(), but this idea is dropped as per Mark's suggestion earlier. The requirement here is, some components have the ability to alter these parameters. Subsequent components in the audio path should me made aware of this.
For example, SRC (sample rate converter) can change 'rate' info coming from hw_param(). Similarly 'mux/demux' can change channel info. Fixing one set of configuration in DT will limit the usage. If this is configurable from user space, then it would be lot more easier.
. . .