Re: [PATCH] ARM: EXYNOS: mcpm: Don't rely on firmware's secondary_cpu_start

[Chander Kashyap]

Hi Doug,

On Tue, Jun 10, 2014 at 9:19 PM, Nicolas Pitre <nicolas.pitre@xxxxxxxxxx> wrote:
> On Tue, 10 Jun 2014, Doug Anderson wrote:
>
>> My S-state knowledge is not strong, but I believe that Lorenzo's
>> questions matter if we're using S2 for CPUidle (where we actually turn
>> off power and hot unplug CPUs) but not when we're using S1 for CPUidle
>> (where we just enter WFI/WFE).
>>

No Its not plain WFI.

All cores in Exynos5420 can be powered off independently.
This functionality has been tested.

Below is the link for the posted patches.

https://lkml.org/lkml/2014/6/10/194

And as Nicolas wrote, these patches need MCPM for that.

>> I believe that in ChromeOS we use S1 CPUidle and that it works fine.
>> We've never implemented S2 that I'm aware of.
>
> You'll have to rely on MCPM for that.  That's probably why it hasn't
> been implemented before.
>
>
> Nicolas
>
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