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Subject: Re: [PATCH 1/2] clocksource/drivers/exynos_mct: Prioritise Arm arch
 timer on arm64
To:     Daniel Lezcano <daniel.lezcano@linaro.org>,
        Will Deacon <will@kernel.org>
Cc:     linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        Marek Szyprowski <m.szyprowski@samsung.com>,
        Krzysztof Kozlowski <krzk@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>,
        Thomas Gleixner <tglx@linutronix.de>
From:   Chanwoo Choi <cw00.choi@samsung.com>
Organization: Samsung Electronics
Message-ID: <4084b547-0bd2-4309-0948-384b81f1026f@samsung.com>
Date:   Tue, 22 Jun 2021 15:42:24 +0900
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References: <20210608154341.10794-1-will@kernel.org>
        <CGME20210608154400epcas1p1b22fd50629611a9475cb4d2b8dd9442d@epcas1p1.samsung.com>
        <20210608154341.10794-2-will@kernel.org>
        <466bfc19-2260-87c6-c458-b43cf23617e3@samsung.com>
        <2a0181ea-a26e-65e9-16f6-cc233b6b296f@linaro.org>
        <fbcd234d-3ea0-d609-1f1d-b557ea329c37@samsung.com>
        <20210617214748.GC25403@willie-the-truck>
        <d79ebd58-1c4e-834c-fc06-482f25f6f3de@linaro.org>
        <20210621101058.GB28788@willie-the-truck>
        <3ba202d9-a679-834a-685f-12c6f9eb9c38@linaro.org>
        <d3e55130-ccfc-4bbc-3c82-91db4ce5113f@samsung.com>
        <1f4d7943-c540-bafd-b372-0d0ed8172f33@linaro.org>
Precedence: bulk

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