[RFC PATCH 0/9] dt: dependencies (for deterministic driver initialization order based on the DT)

Jon Loeliger jdl at jdl.com
Mon Aug 25 06:08:59 PDT 2014


> 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.


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