linux-kernel - Re: [PATCH v9 1/4] clocksource: mips-gic-timer: Enable counter when CPUs start

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Message-ID: <c65a86a5-fc65-4144-b780-ed9e8a59f1ab@linaro.org>
Date: Wed, 19 Feb 2025 13:38:45 +0100
From: Daniel Lezcano <daniel.lezcano@...aro.org>
To: Aleksandar Rikalo <arikalo@...il.com>, linux-mips@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
 Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
 Thomas Gleixner <tglx@...utronix.de>,
 Gregory CLEMENT <gregory.clement@...tlin.com>,
 Serge Semin <fancer.lancer@...il.com>, Jiaxun Yang
 <jiaxun.yang@...goat.com>, Paul Burton <paulburton@...nel.org>,
 Chao-ying Fu <cfu@...s.com>,
 Djordje Todorovic <djordje.todorovic@...cgroup.com>
Subject: Re: [PATCH v9 1/4] clocksource: mips-gic-timer: Enable counter when
 CPUs start

On 29/01/2025 13:32, Aleksandar Rikalo wrote:
> From: Paul Burton <paulburton@...nel.org>
> 
> In multi-cluster MIPS I6500 systems there is a GIC in each cluster,
> each with its own counter. When a cluster powers up the counter will
> be stopped, with the COUNTSTOP bit set in the GIC_CONFIG register.
> 
> In single cluster systems, it has been fine to clear COUNTSTOP once
> in gic_clocksource_of_init() to start the counter. In multi-cluster
> systems, this will only have started the counter in the boot cluster,
> and any CPUs in other clusters will find their counter stopped which
> will break the GIC clock_event_device.
> 
> Resolve this by having CPUs clear the COUNTSTOP bit when they come
> online, using the existing gic_starting_cpu() CPU hotplug callback. This
> will allow CPUs in secondary clusters to ensure that the cluster's GIC
> counter is running as expected.
> 
> 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>
> Reviewed-by: Philippe Mathieu-Daudé <philmd@...aro.org>
> Tested-by: Serge Semin <fancer.lancer@...il.com>
> Tested-by: Gregory CLEMENT <gregory.clement@...tlin.com>
> ---

Acked-by: Daniel Lezcano <daniel.lezcano@...aro.org>


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