linux-kernel - Re: [PATCH 1/2] clocksource/drivers/exynos_mct: Prioritise Arm arch timer on arm64

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Date:   Tue, 22 Jun 2021 15:42:24 +0900
From:   Chanwoo Choi <cw00.choi@...sung.com>
To:     Daniel Lezcano <daniel.lezcano@...aro.org>,
        Will Deacon <will@...nel.org>
Cc:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 1/2] clocksource/drivers/exynos_mct: Prioritise Arm arch
 timer on arm64

On 6/22/21 2:21 PM, Daniel Lezcano wrote:
> On 22/06/2021 04:40, Chanwoo Choi wrote:
>> On 6/21/21 7:18 PM, Daniel Lezcano wrote:
>>> On 21/06/2021 12:10, Will Deacon wrote:
>>>
>>> [ ... ]
>>>
>>>>>> exynos4_mct_frc_start() is called unconditionally from probe via
>>>>>> exynos4_clocksource_init() so as long as the mct probes first, then the
>>>>>> arch timer should work, no? The rating shouldn't affect that.
>>>>>
>>>>> How do you ensure the exynos mct is probed before the arch timer ?
>>>>>
>>>>> The Makefile provides the right order, but the dependency is implicit.
>>>>
>>>> Currently, I think it's done by the order of the CPU hotplug notifiers (
>>>> see the hunk of 6282edb72bed which touches cpuhotplug.h).
>>>
>>> Ah, right. Indeed whatever the DT order, the cpuhotplug order solves the
>>> dependency.
>>>
>>> Chanwoo, are fine with this change ?
>>
>> OK about the order.
>>
>> Actually, I have not fully tested the arch timer on Exynos5433 64bit
>> because of the dependency between arch timer and MCT as we knew.
>>
>> If the Krzysztof and Marek have no any objection,
>> I have no any objection anymore. Thanks.
>>
> 
> Shall I consider it as an Acked-by ?
> 

Unfortunately, it is not acked. Just no objection.
I'm not sure that all cases will be working when using arch timer
because as I said, I have only used the exynos mct timer for all of cases.



-- 
Best Regards,
Chanwoo Choi
Samsung Electronics