sw_params for a direct-ed(dmix) hw pcm

Hi,

On this issue, I am doing something fundamentaly wrong, but I don't see how to do it right.

While configuring a pcm, I should not use sw_params if it is a "direct-ed" (direct::dmix) real hw pcm: in pcm_direct.c, snd_pcm_direct_sw_params function is empty and it seems coherent with the fact the real hw pcm is actually shared and was probably already configured.

How do I know a pcm is actually a "pipeline" of pcms which ends up with a "direct-ed" real hw pcm? That would tell my code how to behave regarding sw_params usage.

Is this related to the "topology" and "ucm" apis?

regards,