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

From: Jon Loeliger
Date: Mon Aug 25 2014 - 09:34:20 EST


> 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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