Re: [PATCH v6 2/7] ACPI: Make ACPI processor driver more extensible

On Wednesday, July 08, 2015 05:57:11 PM Ashwin Chaugule wrote:

On 8 July 2015 at 18:21, Rafael J. Wysocki [off-list ref] wrote:

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On Wednesday, July 08, 2015 05:46:45 PM Ashwin Chaugule wrote:

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On 8 July 2015 at 16:46, Rafael J. Wysocki [off-list ref] wrote:

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Perhaps the confusion is coming from the introduction of ACPI_CST in
this file. I could leave it as it is and just separate out the
ACPI_PSS bits. But I figured, while I'm at it, I'd introduce ACPI_CST,
since we know the LPI stuff is coming up soon as a CST alternative
anyway. So if you prefer, I can drop the CST bits and maybe Sudeep can
address that as part of his LPI patchset?

Yes, please.  That would be much less confusing.

Deja Vu. :)

When I let processor_driver and processor_idle compile on ARM64, I get
a bunch of errors because processor_idle.c contains a lot of X86
specific defines. That is why I'd created the ACPI_CST option which
we'd enable only on X86.

I'm not entirely sure what these enums and functions should default
to, or what they should be on ARM specifically. Given that on ARM64
we're likely to use LPI as against CST, it seems the original approach
is better. Thoughts?

Before we go anywhere deeper, have you checked what happens on ia64?

I dont have access, but I'm really not changing anything functionally.

I mean ia64 is a non-x86 architecture using ACPI.  It very well may be doing
things that you want to be doing.

It looks like the only reason you want ACPI_CST for is to avoid building
processor_idle.c on ARM64.  Then add something like this to the ACPI Kconfig:

config ACPI_PROCESSOR_IDLE
	def_bool Y
	depends on X86 || IA64

and don't make it user-selectable *and* under the ACPI_PROCESSOR config do

	select CPU_IDLE if ACPI_PROCESSOR_IDLE

Then, make processor_idle.c conditional on ACPI_PROCESSOR_IDLE.  That should
do the trick and it may be changed by the LPI series as needed.

Also, I don't see a reason why the ACPI_PSS option should be user-selectable.
I'd call it ACPI_CPU_FREQ_PSS, make it depend on CPU_FREQ and make architectures
select it (or not) as appropriate.

Thanks,
Rafael