Re: [PATCH 2/2] arm64: dts: mt8173: add timer node

[Sudeep Holla <sudeep.holla@arm.com>]

On 01/10/15 15:33, Yingjoe Chen wrote:
> On Thu, 2015-09-17 at 17:13 +0100, Sudeep Holla wrote:
>>

[...]

>>
>> I think your are confusing the system counter with arch timers. System
>> counter is always-on, but the arch timers(logic implementing timers
>> comparators) might not be off when the processor is powered down.
>>
>> I think you need this timer and are using it for low power idle states
>> in which case you will use this as a clock event and not clock source.
>> It will be used as a hardware broadcast event source.
>>
>> There's no call to sched_clock_register in mtk_timer.c, so it can't be
>> the sched clock, so you need to fix the commit log.
>
> Hi Sudeep,
>
> Sorry for late reply.
>
> For sched_clock_register, please see
> http://lists.infradead.org/pipermail/linux-mediatek/2015-July/001547.html
> which was accepted in
> https://git.linaro.org/people/daniel.lezcano/linux.git/shortlog/refs/heads/clockevents/4.4
>

The commit message makes no sense to me. The counters should continue to
work as long as they are in always-on domain. Only timers are lost
when you enter deeper idle states. So I agree with using MTK timer as
broadcast timer/eventsource. You still didn't answer what's the need
to use MTK timer as sched clocksource ?

Regards,
Sudeep