[Ksummit-discuss] [TECH TOPIC] Driver model/resources, ACPI, DT, etc (sigh)

[Linus Walleij]

On Tue, May 6, 2014 at 1:41 PM, Rafael J. Wysocki <rjw at rjwysocki.net> wrote:
> On Monday, May 05, 2014 07:41:04 PM Linus Walleij wrote:
(...)
>> The thing is: with things like BayTrail I already *know* the pin control
>> registers are there, they are just not implemented any handling of.
>> I know very well how much the HW implementers think that a kernel
>> "should never touch" these registers, and I know it will invariably happen
>> sooner or later but like to be proven wrong.
(...)

> That doesn't mean that we can switch x86 to over DTs (that currently is not an
> option for various reasons, not necessarily techical), but we may be able to put
> DT-style information that the current code expects to be there into the ACPI
> tables.

In this case I don't care so much about DT or ACPI or whatever, what
I would like to see is that the hardware is adequately described to
the kernel, and the subsystem has a pretty good idea about how to
describe such hardware, and the idea is *not* per-pin properties
tied to some "GPIO" like I have seen, but concepts like groups and
functions and per-pin configuration tied in to a certain use case.

I know DT is doing it right but that is just because the person who
did the heavy lifting, Stephen Warren, was also a co-author of the
pin control subsystem.

Yours,
Linus Walleij