Re: [RESEND PATCH] ARM: dts: make arch-timer always on in rk3288 soc

[Huang Tao]

Hi,

å 2014å08æ29æ 19:22, Mark Rutland åé:
>> å 2014å08æ28æ 23:11, Mark Rutland åé:
>>> To clarify: if there are low power states that the CPU can enter where
>>> we lose state, then this patch isn't correct.
>> Right now, the software of RK3288 SoC only support CPU hotplug
>> (cpu_on/off) and power off all CPUs on suspend.
> Sure, but that's a Linux implementation detail rather than a fixed
> property of the hardware. Given those states exist, the "always-on"
> property is not appropriate.
>
>> We do not implement cpuidle to power off CPU. Do you think we should
>> introduce a broadcast timer?
> If one is present, yes. 
>
>> On our early kernel, I never see any interrupt on a broadcast timer
>> (yes, we implement it with a external timer).
> That's fine; Linux doesn't need to use it just yet. However, when we
> want to use low power states later, it will be necessary to enable
> placing all CPUS into a low power state.
>
> If your external timer is already supported by an existing driver, there
> is no reason not to add it now.
>
>>> A more general approach would be to enable the broadcast hrtimer for
>>> arm, as has been done for arm64.
>> Yes. I think it should be done by arm framework.
> Patches welcome.
>
> I also think it would make sense to enable this for arm.
>
> Thanks,
> Mark.
>
>
Okay, so this patch is wrong as I expected.
Thank you!

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