Messages in this thread | | | Subject | Re: [PATCH v2 0/5] arm64: sunxi: Enable the sun4i timer | From | Daniel Lezcano <> | Date | Wed, 24 Mar 2021 10:33:06 +0100 |
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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@linaro.org>
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