linux-kernel - [PATCH v5 4/7] clocksource/drivers/exynos_mct: Use percpu interrupts only on ARM64

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Message-ID: <20251023205257.2029526-5-willmcvicker@google.com>
Date: Thu, 23 Oct 2025 20:52:46 +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>, Hosung Kim <hosung0.kim@...sung.com>, 
	Will McVicker <willmcvicker@...gle.com>, Ingo Molnar <mingo@...nel.org>, 
	Peter Griffin <peter.griffin@...aro.org>, Youngmin Nam <youngmin.nam@...sung.com>
Cc: Donghoon Yu <hoony.yu@...sung.com>, Rob Herring <robh@...nel.org>, 
	Saravana Kannan <saravanak@...gle.com>, John Stultz <jstultz@...gle.com>, 
	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, 
	Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Subject: [PATCH v5 4/7] clocksource/drivers/exynos_mct: Use percpu interrupts
 only on ARM64

From: Marek Szyprowski <m.szyprowski@...sung.com>

For some unknown reasons forcing percpu interrupts for local timers
breaks CPU hotplug for 'little' cores on legacy ARM 32bit Exynos based
machines (for example Exynos5422-based Odroid-XU3/XU4 boards). Use percpu
flag only when driver is compiled for newer ARM64 architecture.

Fixes: f3cec54ee3bf ("clocksource/drivers/exynos_mct: Set local timer interrupts as percpu")
Signed-off-by: Marek Szyprowski <m.szyprowski@...sung.com>
Reviewed-by: Peter Griffin <peter.griffin@...aro.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
---
 drivers/clocksource/exynos_mct.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/clocksource/exynos_mct.c b/drivers/clocksource/exynos_mct.c
index a5ef7d64b1c2..1429b9d03a58 100644
--- a/drivers/clocksource/exynos_mct.c
+++ b/drivers/clocksource/exynos_mct.c
@@ -597,7 +597,8 @@ static int __init exynos4_timer_interrupts(struct device_node *np,
 			if (request_irq(mct_irq,
 					exynos4_mct_tick_isr,
 					IRQF_TIMER | IRQF_NOBALANCING |
-					IRQF_PERCPU,
+					(IS_ENABLED(CONFIG_ARM64) ?
+					 IRQF_PERCPU : 0),
 					pcpu_mevt->name, pcpu_mevt)) {
 				pr_err("exynos-mct: cannot register IRQ (cpu%d)\n",
 									cpu);
-- 
2.51.1.821.gb6fe4d2222-goog