Hi Rob,
The remote-endpoint may not be available if it is part of some pluggable module. One such example would be an audio card, the Codec endpoint will not be available until it is plugged in. Hence drop 'remote-endpoint' as a required property.Please hold off on this. I have more changes coming.
OK, I will wait for your patch. Kindly note that this is currently blocking series https://patchwork.kernel.org/project/alsa-devel/list/?series=391735&state=*
Thanks, Sameer.