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

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Date:   Fri, 8 Sep 2023 10:10:37 +0200
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Rafał Miłecki <zajec5@...il.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>, Will Deacon <will@...nel.org>,
        Waiman Long <longman@...hat.com>,
        Boqun Feng <boqun.feng@...il.com>,
        Russell King <linux@...linux.org.uk>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Florian Fainelli <f.fainelli@...il.com>,
        linux-clk@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        openwrt-devel@...ts.openwrt.org,
        bcm-kernel-feedback-list@...adcom.com
Subject: Re: ARM BCM53573 SoC hangs/lockups caused by locks/clock/random changes

Hi Rafal,

On Mon, Sep 4, 2023 at 10:34 AM Rafał Miłecki <zajec5@...il.com> 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()?

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

Yours,
Linus Walleij