linux-kernel - [PATCH v6 3/6] clocksource/drivers/exynos_mct: Set percpu local timer interrupts for ARM64

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Message-ID: <20251120184242.1625820-4-willmcvicker@google.com>
Date: Thu, 20 Nov 2025 18:42:31 +0000
From: Will McVicker <willmcvicker@...gle.com>
To: Russell King <linux@...linux.org.uk>, Catalin Marinas <catalin.marinas@....com>, 
	Will Deacon <will@...nel.org>, Daniel Lezcano <daniel.lezcano@...aro.org>, 
	Thomas Gleixner <tglx@...utronix.de>, Krzysztof Kozlowski <krzk@...nel.org>, 
	Alim Akhtar <alim.akhtar@...sung.com>
Cc: Will McVicker <willmcvicker@...gle.com>, Donghoon Yu <hoony.yu@...sung.com>, 
	Hosung Kim <hosung0.kim@...sung.com>, Rob Herring <robh@...nel.org>, 
	John Stultz <jstultz@...gle.com>, Youngmin Nam <youngmin.nam@...sung.com>, 
	Peter Griffin <peter.griffin@...aro.org>, Tudor Ambarus <tudor.ambarus@...aro.org>, 
	"André Draszik" <andre.draszik@...aro.org>, Conor Dooley <conor+dt@...nel.org>, 
	Marek Szyprowski <m.szyprowski@...sung.com>, linux-samsung-soc@...r.kernel.org, 
	kernel-team@...roid.com, linux-arm-kernel@...ts.infradead.org, 
	linux-kernel@...r.kernel.org
Subject: [PATCH v6 3/6] clocksource/drivers/exynos_mct: Set percpu local timer
 interrupts for ARM64

From: Hosung Kim <hosung0.kim@...sung.com>

To allow the CPU to handle it's own clock events, we need to set the
IRQF_PERCPU flag. This prevents the local timer interrupts from
migrating to other CPUs. This is only supported on ARM64.

Signed-off-by: Hosung Kim <hosung0.kim@...sung.com>
[Original commit from https://android.googlesource.com/kernel/gs/+/03267fad19f093bac979ca78309483e9eb3a8d16]
Reviewed-by: Peter Griffin <peter.griffin@...aro.org>
Reviewed-by: Youngmin Nam <youngmin.nam@...sung.com>
Tested-by: Youngmin Nam <youngmin.nam@...sung.com>
Suggested-by: Marek Szyprowski <m.szyprowski@...sung.com>
Link: https://lore.kernel.org/all/20250827102645.1964659-1-m.szyprowski@samsung.com/
Signed-off-by: Will McVicker <willmcvicker@...gle.com>
---
 drivers/clocksource/exynos_mct.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/clocksource/exynos_mct.c b/drivers/clocksource/exynos_mct.c
index 96361d5dc57d..1429b9d03a58 100644
--- a/drivers/clocksource/exynos_mct.c
+++ b/drivers/clocksource/exynos_mct.c
@@ -596,7 +596,9 @@ static int __init exynos4_timer_interrupts(struct device_node *np,
 			irq_set_status_flags(mct_irq, IRQ_NOAUTOEN);
 			if (request_irq(mct_irq,
 					exynos4_mct_tick_isr,
-					IRQF_TIMER | IRQF_NOBALANCING,
+					IRQF_TIMER | IRQF_NOBALANCING |
+					(IS_ENABLED(CONFIG_ARM64) ?
+					 IRQF_PERCPU : 0),
 					pcpu_mevt->name, pcpu_mevt)) {
 				pr_err("exynos-mct: cannot register IRQ (cpu%d)\n",
 									cpu);
-- 
2.52.0.rc2.455.g230fcf2819-goog