linux-kernel - Re: [PATCH v6 5/5] ACPI : enable ACPI_PROCESSOR

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Date:	Mon, 27 Jun 2016 17:05:11 +0200
From:	Daniel Lezcano <daniel.lezcano@...aro.org>
To:	Sudeep Holla <sudeep.holla@....com>,
	"Rafael J . Wysocki" <rjw@...ysocki.net>,
	linux-acpi@...r.kernel.org
Cc:	Vikas Sajjan <vikas.cha.sajjan@....com>, Sunil <sunil.vl@....com>,
	Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
	Prashanth Prakash <pprakash@...eaurora.org>,
	Al Stone <al.stone@...aro.org>,
	Ashwin Chaugule <ashwin.chaugule@...aro.org>,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v6 5/5] ACPI : enable ACPI_PROCESSOR_IDLE on ARM64

On 06/27/2016 05:03 PM, Sudeep Holla wrote:
> Hi Daniel,
>
> On 27/06/16 15:33, Daniel Lezcano wrote:
>> On 06/14/2016 04:48 PM, Sudeep Holla wrote:
>>> Now that ACPI processor idle driver supports LPI(Low Power Idle), lets
>>> enable ACPI_PROCESSOR_IDLE for ARM64 too.
>>>
>>> This patch just removes the IA64 and X86 dependency on
>>> ACPI_PROCESSOR_IDLE
>>>
>>> Cc: linux-arm-kernel@...ts.infradead.org
>>> Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>
>>> Signed-off-by: Sudeep Holla <sudeep.holla@....com>
>>> ---
>>
>> Hi Sudeep,
>>
>> now that ACPI processor supports ARM64 did you check the
>> CPUIDLE_DRIVER_STATE_START trick in the code and its derivative ?
>>
>
> No, that is used only for C-State and ARM64 doesn't support it.
> Patch 1/5 puts all the C-State code under #ifdef so that it's not
> compiled on ARM64.
>
>> I deleted the patch 2/5 but there is a place where:
>>
>
> Sorry, I don't follow what you mean by that.

I meant I just deleted from my mailbox the patch 2/5, so I can't do 
inline comment.

>> if (max_cstate=0)
>>      max_cstate=1;
>>
>> Probably this is because the POLL state is inserted, so there is always
>> an idle state. But for ARM, that is not the case.
>>
>
> Yes
>
>> Also, there are some places where the idle state index begins to 1. I
>> think it should be 0 for ARM.
>>
>
> Yes for LPI, it does start from 0.
>


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