PROBLEM: BUG appearing when trying to allocate interrupt on Exynos MCT after CPU hotplug
Daniel Lezcano
daniel.lezcano at linaro.org
Sat Jan 31 01:21:54 PST 2015
On 01/31/2015 02:08 AM, Stephen Boyd wrote:
> Kept meaning to get back to this thread. Have you resolved it?
>
> On 10/29/14 03:38, Marcin Jabrzyk wrote:
>> So I've tried this patch, it resolves one problem but introduces also
>> new ones. As expected the BUG warning is not showing after applying
>> this patch but there are some interesting side effects.
>
> Well that's half good news.
>
>> I was looking on /proc/interrupts output. IRQ for CPU0 have "MCT" name
>> and IRQ for CPU1 has unexpectedly no name at all.
>
> This is pretty confusing. I don't see how the patch could cause this to
> happen.
>
>> After making hotplug cycle of CPU1 I've observed that IRQs attached
>> originally for that CPU are generating on really low count and not in
>> order with IRQ for CPU0.
>> What's more the interrupt for CPU1 is showing to me as being counted
>> for both CPUs, so it's probably not being attached to CPU1.
>>
>
> yeah. Can you give the output of /proc/timer_list in addition to
> /proc/interrupts? It may give some hints on what's going on. It may also
> be interesting to see if irq_force_affinity() is failing. Please check
> the return value and print an error
Hi Stephen, Marcin,
can you have a look if the patch [1] fixes this issue ?
-- Daniel
[1] https://lkml.org/lkml/2015/1/30/423
> diff --git a/drivers/clocksource/exynos_mct.c b/drivers/clocksource/exynos_mct.c
> index 1800053b4644..3c4538e26731 100644
> --- a/drivers/clocksource/exynos_mct.c
> +++ b/drivers/clocksource/exynos_mct.c
> @@ -450,6 +450,7 @@ static int exynos4_local_timer_setup(struct clock_event_device *evt)
> {
> struct mct_clock_event_device *mevt;
> unsigned int cpu = smp_processor_id();
> + int ret;
>
> mevt = container_of(evt, struct mct_clock_event_device, evt);
>
> @@ -468,7 +469,9 @@ static int exynos4_local_timer_setup(struct clock_event_device *evt)
> if (mct_int_type == MCT_INT_SPI) {
> evt->irq = mct_irqs[MCT_L0_IRQ + cpu];
> enable_irq(evt->irq);
> - irq_force_affinity(mct_irqs[MCT_L0_IRQ + cpu], cpumask_of(cpu));
> + ret = irq_force_affinity(mct_irqs[MCT_L0_IRQ + cpu], cpumask_of(cpu));
> + if (ret)
> + pr_err("force failed %d\n", ret);
> } else {
> enable_percpu_irq(mct_irqs[MCT_L0_IRQ], 0);
> }
>
--
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