Re: [PATCH v2 0/5] arm64: sunxi: Enable the sun4i timer

[Daniel Lezcano]

On 24/03/2021 04:51, Samuel Holland wrote:
> On 3/22/21 9:18 AM, Daniel Lezcano wrote:
>> On 22/03/2021 05:47, Samuel Holland wrote:
>>> In preparation for adding CPU idle states, hook up the sun4i timer.
>>> Having a non-c3stop clockevent source available is necessary for all
>>> CPUs to simultaneously enter a local-timer-stop idle state.
>>
>> Why simultaneously ?
> Because the CPU providing (the hrtimer providing) the broadcast timer
> cannot enter an idle state which would stop that timer. So in my case,
> with 4 CPUs, I was seeing at most 3 CPUs enter idle at any given time.
> This prevented any cluster-level idle states from doing anything. After
> applying this series, I was able to observe the whole cluster powering
> down when appropriate.

Ah, ok. I did not realize this fourth CPU was acting as the broadcast
timer, so allowing at least a CPU power down. This setup is unusual.

The changes make sense.

Acked-by: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>



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