On Wed, Oct 07, 2020 at 09:19:32AM -0700, Dan Williams wrote:
> On Wed, Oct 7, 2020 at 2:14 AM gregkh@linuxfoundation.org

> > "virtual" here means "not real" :)

> Which of these aux device use cases is not a real device? One of my
> planned usages for this facility is for the NPEM (Native PCIE
> Enclosure Management) mechanism that can appear on any PCIE
> bridge/endpoint. While it is true that the NPEM register set does not
> get its own PCI-b:d:f address on the host bus, it is still
> discoverable by a standard enumeration scheme. It is real auxiliary
> device functionality that can appear on any PCIE device where the
> kernel can now have one common NPEM driver for all instances in the
> topology.

Some if not all of the SOF cases are entirely software defined by the
firmware downloaded to the audio DSPs.