On Thu, Jul 02, 2020 at 04:46:09PM +0200, Frieder Schrempf wrote:

> My intention is to use the spidev driver in the default board DT for an
> interface that is routed to an extension connector and has no dedicated
> slave device attached onboard. So users can attach sensors, etc. with
> userspace drivers without touching the kernel or DT.

The expected way of doing this is to describe whatever was attached via
DT when it's attached - the device is what has the compatible, not some
connector in the middle of the connection.  The way you've got things
set up if the device has a driver then they won't be able to instantiate
the driver.