[GIT PULL] On-demand device probing

Mark Brown broonie at kernel.org
Mon Oct 19 09:04:00 PDT 2015


On Mon, Oct 19, 2015 at 04:29:40PM +0100, David Woodhouse wrote:
> On Mon, 2015-10-19 at 15:50 +0100, Mark Brown wrote:
> > > But the point I'm making is that we are working towards *fixing* that,
> > > and *not* using DT-specific code in places where we should be using the
> > > generic APIs.

> > What is the plan for fixing things here?  It's not obvious (at least to
> > me) that we don't want to have the subsystems having knowledge of how
> > they are bound to a specific firmware which is what you seem to imply
> > here. 

> I don't know that there *is* a coherent plan here to address it all.

> Certainly, we *will* need subsystems to have firmware-specific
> knowledge in some cases. Take GPIO as an example; ACPI *has* a way to
> describe GPIO, and properties which reference GPIO pins are intended to
> work through that — while in DT, properties which reference GPIO pins
> will have different contents. They'll be compatible at the driver
> level, in the sense that there's a call to get a given GPIO given the
> property name, but the subsystems *will* be doing different things
> behind the scenes.

I'd expect that to be the norm rather than the exception.

> > It seems like we're going to have to refactor these bits of code when
> > they get generalised anyway so I'm not sure that the additional cost
> > here is that big.

> That's an acceptable answer — "we're adding legacy code here but we
> know it's going to be refactored anyway". If that's true, all it takes
> is a note in the commit comment to that effect. That's different from
> having not thought about it :)

Given the above I'm not even sure it's legacy code, it's just as likely
we're going to get some parallel ACPI code added to the subsystems for
parsing their bindings.
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