[Ksummit-discuss] [TECH TOPIC] Addressing complex dependencies and semantics (v2)

[Mark Brown]

On Wed, Jul 27, 2016 at 09:50:04AM -0700, Luis R. Rodriguez wrote:

> Rafael has proposed has a set of patches to help deal with functional
> dependencies between devices to help with power management. Mauro has

This wasn't purely for PM, it should also help with probe ordering
(hopefully).

> spoken briefly before over the media controller feature graph used to help
> build relationship between complex dynamic dependencies. Dmitry has taken on

> to help enable asynchronous probe, however for built-in devices this requires
> very specific platform knowledge otherwise using async probe will blow up
> your kernel -- if you get it right though, using async probe can help with

I'm not sure what specific platform knowledge you're thinking of here?
We have coverage for most things in the form of deferred probe (messy
though it is).

> This begs a few questions:

>  o Are there generic issues here ?
>  o Are there generic solutions possible ?
>  o What advanced techniques are out there to deal with this and how
>    are efforts in those domains going ?

There's definitely a lot of overlap in the runtime PM and probe parts of
things, and the various composite devices (media controller, ASoC and so
on) also share a lot.

> Folks required to help with these topics:

>   o Dmitry Torokhov <dmitry.torokhov at gmail.com> (async probe)
>   o "Rafael J. Wysocki" <rafael.j.wysocki at intel.com> (functional dependencies)
>   o Marek Szyprowski <m.szyprowski at samsung.com> (taking on some of
> Rafael's previous work)
>   o Mauro Carvalho Chehab <mchehab at osg.samsung.com> (feature graph)
>   o Vegard Nossum <vegard.nossum at gmail.com> (SAT)
>   o Valentin Rothberg <valentinrothberg at gmail.com>  (wary of some
> kconfig issues)

Probably worth me being involved as well, regulators seem to be among
the devices with most visible PM related ordering issues since they are
typically on slow buses and ASoC is all about composite devices.
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