acpi_cpu: _PDC vs _OSC

[Andriy Gapon]

What do you think about changing logic of evaluating _PDC and _OSC for Processor
object in acpi_cpu_attach?
It seems that later versions of ACPI standard deprecate _PDC in favor of _OSC.
Although, in practice they seem to be present or not present together, sometimes
_PDC being only a wrappper around _OSC.  There are still, of course, systems with
only _PDC present.  I assume that there are systems with only _OSC too.

I would like to change the order, so that _OSC evaluation is attempted first and
only if it fails then proceed with _PDC.

Also, I would like to print status returned by _OSC (in case of successful
evaluation) if it is not zero. (Note: this is not the same as status of evaluating
_OSC).

And I am going to fix the following comment:
* On some systems we need to evaluate _OSC so that the ASL
* loads the _PSS and/or _PDC methods at runtime.

Although on many systems either _PDC or _OSC or both dynamically load SSDTs that
contain additional Processor objects like _PSS and _PCT, I haven't seen any system
where _OSC would load _PDC.  And, honestly, that wouldn't make any sense.
Perhaps, comment's author meant _PCT in place of _PDC, or something like that.

Please let me know what you think.
Thanks!

Convenience link:
http://download.intel.com/technology/IAPC/acpi/downloads/30222305.pdf
-- 
Andriy Gapon