On Thu, Feb 25, 2021 at 10:52:43AM +0800, Shengjiu Wang wrote:

Imx-rpmsg is a new added machine driver for supporting audio on Cortex-M
core. The Cortex-M core will control the audio interface, DMA and audio
codec, setup the pipeline, the audio driver on Cortex-A core side is just
to communitcate with M core, it is a virtual sound card and don't touch
the hardware.

This sounds like 1 h/w block (the interface to the cortex-M), your DT 
should be 1 node. If you need 2 drivers to satisfy the needs of the OS, 
then instantiate one device from the other device's driver.

Rob