Re: PROBLEM:ÂBUG appearing when trying to allocate interrupt on Exynos MCT after CPU hotplug

[Marcin Jabrzyk]

On 31/01/15 10:21, Daniel Lezcano wrote:
> 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
Hi Daniel,

I've checked this patch on the board that have problems and it fixes 
this issue completely. Everything looks fine after power cycle of the CPU.

Best regards,
Marcin Jabrzyk

> > 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);
> >       }

--
Samsung R&D Institute Poland
Samsung Electronics
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