On 06/18/18 00:45, Linus Walleij wrote:

This is a proposal for how to handle the non-discoverable
96boards plug-in expansion boards called "mezzanines" in the
Linux kernel. It is a working RFC series meant for discussion
at the moment.

< snip >

So for that reason, or other predictable statements such
as "you're reinventing board files", I'd like to have an
open discussion on how to actually support these boards
with the mainline kernel and work on device drivers common
with other systems now, and not in 2020 when they are already
obsolete.

Yeah it is a bit controversial, but what we are doing right
now for non-discoverable expansion boards isn't working
in my opinion, so I have to throw something out there,
and this is it.

< snip >

why  can't a devicetree description of the devices on the
mezzanine board be used?

I do understand the desire to describe interchangeable mezzanine
boards separately from the base devicetree, such as in an
overlay.  Overlays can be applied today by U-boot before the
Linux kernel is booted, so lack of being able to apply an
overlay after Linux boot completes is not a blocker.

-Frank