Re: ARM BCM53573 SoC hangs/lockups caused by locks/clock/random changes

[Rafał Miłecki]

Hi,

it's a late reply but I didn't find enough determination earlier.

On 8.09.2023 10:10, Linus Walleij wrote:
> On Mon, Sep 4, 2023 at 10:34 AM Rafał Miłecki <zajec5@xxxxxxxxx> wrote:
>
> > I'm clueless at this point.
> > Maybe someone can come up with an idea of actual issue & ideally a
> > solution.
>
> Damn this is frustrating.
>
> > 2. Clock (arm,armv7-timer)
> >
> > While comparing main clock in Broadcom's SDK with upstream one I noticed
> > a tiny difference: mask value. I don't know it it makes any sense but
> > switching from CLOCKSOURCE_MASK(56) to CLOCKSOURCE_MASK(64) in
> > arm_arch_timer.c (to match SDK) increases average uptime (time before a
> > hang/lockup happens) from 4 minutes to 36 minutes.
>
> This could be related to how often the system goes to idle.
>
> > +       if (cpu_idle_force_poll == 1234)
> > +               arch_cpu_idle();
> > +       if (cpu_idle_force_poll == 5678)
> > +               arch_cpu_idle();
> > +       if (cpu_idle_force_poll == 1234)
> > +               arch_cpu_idle();
> > +       if (cpu_idle_force_poll == 5678)
> > +               arch_cpu_idle();
> > +       if (cpu_idle_force_poll == 1234)
> > +               arch_cpu_idle();
> > +       if (cpu_idle_force_poll == 5678)
> > +               arch_cpu_idle();
> > +       if (cpu_idle_force_poll == 1234)
> > +               arch_cpu_idle();
>
> Idle again.
>
> I would have tried to see what arch_cpu_idle() is doing.
>
> arm_pm_idle() or cpu_do_idle()?

In my case arm_pm_idle is NULL.


> What happens if you just put return in arch_cpu_idle()
> so it does nothing?

Doesn't help. I also tried putting:
udelay(10);
and
udelay(1000);
at the arch_cpu_idle() beginning. None helped.


Here comes more interesting experiment though. Putting there:

if (!(foo++ % 10000)) {
	pr_info("[%s] arm_pm_idle:%ps\n", __func__, arm_pm_idle);
}

doesn't seem to help.


Putting following however seems to make kernel/device stable:

if (!(foo++ % 100)) {
	pr_info("[%s] arm_pm_idle:%ps\n", __func__, arm_pm_idle);
}


I think I'm just going to assume those chipsets are simply hw broken.