* [PATCH] clocksource/drivers/exynos_mct: Use percpu interrupts only on ARM64
[not found] <CGME20250827102650eucas1p1fe270adbf29c649b9ce529e1d45aabc3@eucas1p1.samsung.com>
@ 2025-08-27 10:26 ` Marek Szyprowski
2025-08-27 11:58 ` Krzysztof Kozlowski
0 siblings, 1 reply; 2+ messages in thread
From: Marek Szyprowski @ 2025-08-27 10:26 UTC (permalink / raw)
To: linux-arm-kernel, linux-samsung-soc
Cc: Marek Szyprowski, Daniel Lezcano, Thomas Gleixner,
Krzysztof Kozlowski, Alim Akhtar, Ingo Molnar, Peter Griffin,
Youngmin Nam
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@samsung.com>
---
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 62febeb4e1de..fece6bbc190e 100644
--- a/drivers/clocksource/exynos_mct.c
+++ b/drivers/clocksource/exynos_mct.c
@@ -603,7 +603,8 @@ 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);
--
2.34.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] clocksource/drivers/exynos_mct: Use percpu interrupts only on ARM64
2025-08-27 10:26 ` [PATCH] clocksource/drivers/exynos_mct: Use percpu interrupts only on ARM64 Marek Szyprowski
@ 2025-08-27 11:58 ` Krzysztof Kozlowski
0 siblings, 0 replies; 2+ messages in thread
From: Krzysztof Kozlowski @ 2025-08-27 11:58 UTC (permalink / raw)
To: Marek Szyprowski, linux-arm-kernel, linux-samsung-soc
Cc: Daniel Lezcano, Thomas Gleixner, Alim Akhtar, Ingo Molnar,
Peter Griffin, Youngmin Nam
On 27/08/2025 12:26, Marek Szyprowski wrote:
> 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")
I am pretty sure the patch above was not tested on arm32, thus this
workaround seems reasonable.
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Best regards,
Krzysztof
^ permalink raw reply [flat|nested] 2+ messages in thread
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2025-08-27 10:26 ` [PATCH] clocksource/drivers/exynos_mct: Use percpu interrupts only on ARM64 Marek Szyprowski
2025-08-27 11:58 ` Krzysztof Kozlowski
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