Anyway, instead of going back and forth between "deferred probe is good"
and "deferred probe is bad", how about we do something useful now and
concentrate on how to make use of the information we have in DT with the
goal to reduce the number of cases where deferred probing is required?

Good idea.

The proposal on the table is to allow the probe code
to make a topological sort of the devices based on
dependency information either implied, explicitly stated
or both.  That is likely a fundamentally correct approach.

I believe some of the issues that need to be resolved are:

    1) What constitutes a dependency?
    2) How is that dependency expressed?
    3) How do we add missing dependencies?
    4) Backward compatability problems.

There are other questions, of course.  Is it a topsort
per bus?  Are there required "early devices"?  Should
the inter-node dependencies be expressed at each node,
or in a separate hierarchy within the DTS?  Others.

HTH,
jdl