Re: [Linaro-acpi] [RFC] ACPI on arm64 TODO List

G Gregory
2014-12-17T09:08:44Z

On 17 December 2014 at 00:37, Al Stone <al.stone@linaro.org> wrote:
>> I have not seen good guidelines on the usage of _DSD in that respect,
>> and I'm worried we'll end up with clock controllers half-owned by AML
>> and half-owned by the kernel's clock framework, and this separation
>> varying from board to board (and FW revision to FW revision). I think
>> that needs to be clarified at the ACPI spec level in addition to
>> anything we have in the kernel documentation.
>
> Hrm. The spec (section 6.2.5) basically says that there exists a
> thing called _DSD and that when invoked, it returns a UUID followed
> by a data structure. A separate document (on http://www.uefi.org/acpi)
> for each UUID defines the data structure it corresponds to. The only
> one defined so far is for device properties:
>
>
> http://www.uefi.org/sites/default/files/resources/_DSD-implementation-guide-toplevel.htm
>
> I think you are suggesting good guidelines for both, yes? The usage
> of new UUIDs and data structures, along with the usage of device
> properties for the UUID we have, right? I've been trying to write
> such a thing but all I've accomplished so far is throwing away a
> couple of drafts that got ugly. I'll keep at it, though.
>

Of course the way the spec is written also gives us the option, if the
OEMs and kernel guys and MS all agree on a different format for
aarch64 then all that is needed is a new UUID and we are no longer
tied to trying to insert DT into ACPI. I personally think this is the
way to go, I do not like the blindly copying DT into ACPI. I suspect
the information that a ACPI platform "needs" is probably significantly
simplified compared to some of the DT bindings.

Graeme