linux-kernel - Re: [PATCH v7 05/12] clocksource: mips-gic-timer: Always use cluster 0 counter as clocksource

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Message-ID: <afda1ccc-d9fc-4025-b114-bd2ddf5f7ec1@linaro.org>
Date: Mon, 28 Oct 2024 16:22:55 +0100
From: Daniel Lezcano <daniel.lezcano@...aro.org>
To: Thomas Bogendoerfer <tsbogend@...ha.franken.de>
Cc: Aleksandar Rikalo <arikalo@...il.com>, Chao-ying Fu <cfu@...ecomp.com>,
 Geert Uytterhoeven <geert@...ux-m68k.org>, Greg Ungerer <gerg@...nel.org>,
 Hauke Mehrtens <hauke@...ke-m.de>,
 Ilya Lipnitskiy <ilya.lipnitskiy@...il.com>,
 Jiaxun Yang <jiaxun.yang@...goat.com>, linux-kernel@...r.kernel.org,
 linux-mips@...r.kernel.org, Marc Zyngier <maz@...nel.org>,
 Paul Burton <paulburton@...nel.org>, Peter Zijlstra <peterz@...radead.org>,
 Serge Semin <fancer.lancer@...il.com>, Thomas Gleixner <tglx@...utronix.de>,
 Tiezhu Yang <yangtiezhu@...ngson.cn>,
 Gregory CLEMENT <gregory.clement@...tlin.com>
Subject: Re: [PATCH v7 05/12] clocksource: mips-gic-timer: Always use cluster
 0 counter as clocksource

On 28/10/2024 16:15, Thomas Bogendoerfer wrote:
> On Mon, Oct 28, 2024 at 03:54:48PM +0100, Daniel Lezcano wrote:
>> On 19/10/2024 09:10, Aleksandar Rikalo wrote:
>>> From: Paul Burton <paulburton@...nel.org>
>>>
>>> In a multi-cluster MIPS system, there are multiple GICs - one in each
>>> cluster - each of which has its independent counter. The counters in
>>> each GIC are not synchronized in any way, so they can drift relative
>>> to one another through the lifetime of the system. This is problematic
>>> for a clock source which ought to be global.
>>>
>>> Avoid problems by always accessing cluster 0's counter, using
>>> cross-cluster register access. This adds overhead so it is applied only
>>> on multi-cluster systems.
>>>
>>> Signed-off-by: Paul Burton <paulburton@...nel.org>
>>> Signed-off-by: Chao-ying Fu <cfu@...ecomp.com>
>>> Signed-off-by: Dragan Mladjenovic <dragan.mladjenovic@...mia.com>
>>> Signed-off-by: Aleksandar Rikalo <arikalo@...il.com>
>>> Tested-by: Serge Semin <fancer.lancer@...il.com>
>>> ---
>>
>> May I take this patch through the clocksource tree ?
> 
> sure, should be the best option.

Ok, thanks

Can you add your tag ?


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