[RFC PATCH 0/9] dt: dependencies (for deterministic driver initialization order based on the DT)
holler at ahsoftware.de
Tue Aug 26 03:18:35 PDT 2014
Am 26.08.2014 10:51, schrieb Grant Likely:
> Getting the dependency tree I think is only half the problem. The other
> have is how to get the driver model to actually order probing using that
> list. That problem is hard because the order drivers are probed is
> currently determined by the interaction of driver link order, driver
> initcall level, and device registration order. The first devices are
> registered at an early initcall, before their drivers, and therefore
> bind order is primarily determined by initcall level and driver link
> order. However, later devices (ie. i2c clients) are registered by the
> bus driver (ie. again, i2c) and probe order may be primarily link order
> (if the driver is not yet registered) or registration order (if the
> driver was registered before the parent bus).
Using my patches, the problem which still exists is how to handle
devices (not drivers). I've build the patches based on the assumption
that device-handling happens automatically. Unfortunately that isn't
really true and device-handling looks awkward. Some drivers build them
themself, some require that a device already exists and some require
that a device doesn't already exist.
But I haven't looked in deep at that. I'm sure that can be fixed by
fixing drivers which do things differently than they should (maybe
because they needed to do such for dirty workarounds because no order
was guaranteed, which wouldn't be true anymore).
Anyway, I've not looked further into that problem (with devices, not
drivers) as it already seems quiet impossible to get the other necessary
stuff into the kernel in a reasonable time (before 32bit-HW which does
use DT will not be available anymore).
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