[Ksummit-2013-discuss] [ATTEND] ACPI vs DT

[Rafael J. Wysocki]

On Thursday, July 25, 2013 10:16:28 AM Linus Walleij wrote:
> On Thu, Jul 25, 2013 at 1:05 AM, Rafael J. Wysocki <rjw at sisk.pl> wrote:
> 
> > If you want a platform device to be created automatically for an object with
> > a particular PNP ID, add that PNP ID to acpi_platform_device_ids[] in
> > drivers/acpi/acpi_platform.c.  Then, you'll be able to match your driver to
> > that platform device using acpi_match_table, as described in
> > Documentation/acpi/enumeration.txt.
> >
> > Of course, that's going to work only if the ACPI namespace contains an object
> > with that PNP ID.  Now, you can ask me "What to do if it doesn't?" and that's
> > a good question.
> 
> Hm this fits well into the topic of the thread.
> 
> Atleast it seems like ACPI+ioport detection should be possible to
> combine in the same driver, so that if no PNP ID is found through
> ACPI, it can fall back to the ioport probing.

Yes, that's viable in my opinion.

> In the ARM community we're basically telling people to go fix their
> device trees if things are missing from them, so I was thinking
> if it is proper to ask x86 ACPI system vendors to go fix their AML
> and provide proper DSDTs.
> 
> I understand we cannot do this for deployed systems, but for
> systems in development we should provide some pushback,
> maybe?

Yes, for systems in development it would be good to indicate what our
expectations are at least (ie. we expect all devices to be represented in the
ACPI namespace unless they can be discovered natively, like PCI).

Thanks,
Rafael


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.