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

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Message-ID: <d3e55130-ccfc-4bbc-3c82-91db4ce5113f@samsung.com>
Date:   Tue, 22 Jun 2021 11:40:50 +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 6/21/21 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.

-- 
Best Regards,
Chanwoo Choi
Samsung Electronics