On Tue, 15 Apr 2014, Krzysztof Kozlowski wrote:

On wto, 2014-04-15 at 14:28 +0200, Daniel Lezcano wrote:

quoted

On 04/15/2014 11:34 AM, Krzysztof Kozlowski wrote:

quoted

On pi?, 2014-03-28 at 14:06 +0100, Krzysztof Kozlowski wrote:

quoted

Fix stall after hotplugging CPU1. Affected are SoCs where Multi Core Timer
interrupts are shared (SPI), e.g. Exynos 4210. The stall was a result of
starting the CPU1 local timer not in L1 timer but in L0 (which is used
by CPU0).

Hi,

Do you have any comments on these 3 patches? They fix the CPU stall on
Exynos4210 and also on Exynos3250 (Chanwoo Choi sent patches for it
recently).

You describe this issue as impacting different SoC not only the exynos, 
right ?

Do you know what other SoCs are impacted by this ?

No, affected are only Exynos SoC-s. It was confirmed on Exynos4210
(Trats board) and Exynos3250 (new SoC, patches for it were recently
posted by Chanwoo).

Other Exynos SoC-s where MCT local timers use shared interrupts (SPI)
can also be affected. Candidates are Exynos 5250 and 5420 but I haven't
tested them.

quoted

I guess this issue is not reproducible just with the line below, we need 
a timer to expire right at the moment CPU1 is hotplugged, right ?

Right. The timer must fire in short time between enabling local timer
for CPU1 and setting the affinity for IRQ.

Why do you set the affinity in the CPU_ONLINE hotplug callback and not
right away when the interrupt is requested?

Thanks,

	tglx


Index: linux-2.6/drivers/clocksource/exynos_mct.c
===================================================================

--- linux-2.6.orig/drivers/clocksource/exynos_mct.c
+++ linux-2.6/drivers/clocksource/exynos_mct.c

@@ -430,6 +430,7 @@ static int exynos4_local_timer_setup(str
 				evt->irq);
 			return -EIO;
 		}
+		irq_set_affinity(mct_irqs[MCT_L0_IRQ + cpu], cpumask_of(cpu));
 	} else {
 		enable_percpu_irq(mct_irqs[MCT_L0_IRQ], 0);
 	}

@@ -461,12 +462,6 @@ static int exynos4_mct_cpu_notify(struct
 		mevt = this_cpu_ptr(&percpu_mct_tick);
 		exynos4_local_timer_setup(&mevt->evt);
 		break;
-	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);
 		exynos4_local_timer_stop(&mevt->evt);