[patch added to the 3.12 stable tree] clocksource: Exynos_mct: Use irq_force_affinity() in cpu bringup

Jiri Slaby jslaby at suse.cz
Fri Jun 6 05:49:21 PDT 2014

From: Thomas Gleixner <tglx at linutronix.de>

This patch has been added to the 3.12 stable tree. If you have any
objections, please let us know.


commit 30ccf03b4a6a2102a2219058bdc6d779dc637dd7 upstream.

The starting cpu is not yet in the online mask so irq_set_affinity()
fails which results in per cpu timers for this cpu ending up on some
other online cpu, ususally cpu 0.

Use irq_force_affinity() which disables the online mask check and
makes things work.

Signed-off-by: Thomas Gleixner <tglx at linutronix.de>
Tested-by: Krzysztof Kozlowski <k.kozlowski at samsung.com>
Cc: Kyungmin Park <kyungmin.park at samsung.com>
Cc: Marek Szyprowski <m.szyprowski at samsung.com>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie at samsung.com>
Cc: Tomasz Figa <t.figa at samsung.com>,
Cc: Daniel Lezcano <daniel.lezcano at linaro.org>,
Cc: Kukjin Kim <kgene.kim at samsung.com>
Cc: linux-arm-kernel at lists.infradead.org,
Link: http://lkml.kernel.org/r/20140416143316.106665251@linutronix.de
Signed-off-by: Thomas Gleixner <tglx at linutronix.de>
Signed-off-by: Jiri Slaby <jslaby at suse.cz>
 drivers/clocksource/exynos_mct.c | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/drivers/clocksource/exynos_mct.c b/drivers/clocksource/exynos_mct.c
index 62b0de6a1837..b17b3e0981f0 100644
--- a/drivers/clocksource/exynos_mct.c
+++ b/drivers/clocksource/exynos_mct.c
@@ -428,6 +428,7 @@ static int exynos4_local_timer_setup(struct clock_event_device *evt)
 			return -EIO;
+		irq_force_affinity(mct_irqs[MCT_L0_IRQ + cpu], cpumask_of(cpu));
 	} else {
 		enable_percpu_irq(mct_irqs[MCT_L0_IRQ], 0);
@@ -448,7 +449,6 @@ static int exynos4_mct_cpu_notify(struct notifier_block *self,
 					   unsigned long action, void *hcpu)
 	struct mct_clock_event_device *mevt;
-	unsigned int cpu;
 	 * Grab cpu pointer in each case to avoid spurious
@@ -459,12 +459,6 @@ static int exynos4_mct_cpu_notify(struct notifier_block *self,
 		mevt = this_cpu_ptr(&percpu_mct_tick);
-	case CPU_ONLINE:
-		cpu = (unsigned long)hcpu;
-		if (mct_int_type == MCT_INT_SPI)
-			irq_set_affinity(mct_irqs[MCT_L0_IRQ + cpu],
-						cpumask_of(cpu));
-		break;
 	case CPU_DYING:
 		mevt = this_cpu_ptr(&percpu_mct_tick);

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