Re: [PATCH v6 4/5] arm64: add support for ACPI Low Power Idle(LPI)

From	Sudeep Holla <sudeep.holla@arm.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v6 4/5] arm64: add support for ACPI Low Power Idle(LPI)
Date	2016-06-27 20:00 +0200
Message-ID	<rOIZc-3tG-33@gated-at.bofh.it> (permalink)
References	<rJXPc-66e-13@gated-at.bofh.it> <rJXPd-66e-55@gated-at.bofh.it> <rMRax-4xg-17@gated-at.bofh.it> <rOHA6-2Ez-37@gated-at.bofh.it> <rOIcN-39i-1@gated-at.bofh.it>
Organization	ARM

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On 27/06/16 18:07, Sudeep Holla wrote:
>
>
> On 27/06/16 17:29, Daniel Lezcano wrote:

[...]

>>
>> acpi_disabled - acpi_disabled - acpi_disabled everywhere :/
>>
>> The enable-method approach is not straightforward and now it is polluted
>> by acpi-disabled.
>>
>> So IIUC,
>>
>> smp_init_cpus (contains acpi_disabled)
>>    smp_cpu_setup
>>      cpu_read_ops
>>        cpu_read_enable_method (contains acpi_disabled)
>>          acpi_get_enable_method (returns 'psci' after checking
>> psci_is_present)
>>
>> Then psci_cpu_init_idle is called... and check again acpi_disabled.
>>
>> IMO, the circumlocution with the psci vs acpi vs acpi_disabled is
>> getting unnecessary too complex, is prone to error and will lead to
>> unmaintainable code very soon.
>>
>> I suggest to sort out encapsulation and self-contained code before
>> adding more feature in this area.
>>
>
> I understand your concern but I have no idea on how to clean up. Lorenzo
> asked to factor our common code between psci_{dt,acpi}_cpu_init_idle and
> I think you might not like the refactoring[1]. I didn't want to change
> cpuidle_ops and hence psci_dt_cpu_init_idle parameters. I will see if
> changing that simplifies things.
>

One of the reasons for adding acpi_disabled check is to keep the other
logic at the same place. Otherwise we end up duplicating that code which
is what I have done in psci_{dt,acpi}_cpu_init_idle at the first place.

-- 
Regards,
Sudeep

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Re: [PATCH v6 4/5] arm64: add support for ACPI Low Power Idle(LPI) Daniel Lezcano <daniel.lezcano@linaro.org> - 2016-06-27 18:30 +0200
  Re: [PATCH v6 4/5] arm64: add support for ACPI Low Power Idle(LPI) Sudeep Holla <sudeep.holla@arm.com> - 2016-06-27 19:10 +0200
    Re: [PATCH v6 4/5] arm64: add support for ACPI Low Power Idle(LPI) Sudeep Holla <sudeep.holla@arm.com> - 2016-06-27 20:00 +0200

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