Re: [PATCH v3 08/16] irqchip/gic: Configure SGIs as standard interrupts

Jon Hunter
2020-09-16T16:42:58Z

On 16/09/2020 16:10, Marc Zyngier wrote:
> Hi Jon,
>
> +Linus, who is facing a similar issue.
>
> On 2020-09-16 15:16, Jon Hunter wrote:
>> Hi Marc,
>>
>> On 14/09/2020 14:06, Marek Szyprowski wrote:
>>> Hi Marc,
>>>
>>> On 01.09.2020 16:43, Marc Zyngier wrote:
>>>> Change the way we deal with GIC SGIs by turning them into proper
>>>> IRQs, and calling into the arch code to register the interrupt range
>>>> instead of a callback.
>>>>
>>>> Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
>>>> Signed-off-by: Marc Zyngier <maz@kernel.org>
>>> This patch landed in linux next-20200914 as commit ac063232d4b0
>>> ("irqchip/gic: Configure SGIs as standard interrupts"). Sadly it breaks
>>> booting of all Samsung Exynos 4210/4412 based boards (dual/quad ARM
>>> Cortex A9 based). Here are the last lines from the bootlog:
>>
>> I am observing the same thing on several Tegra boards (both arm and
>> arm64). Bisect is pointing to this commit. Reverting this alone does not
>> appear to be enough to fix the issue.
>
> Right, I am just massively by the GICv3 spec, and failed to remember
> that ye olde GIC exposes the source CPU in AIR *and* wants it back, while
> newer GICs deal with that transparently.
>
> Can you try the patch below and let me know?

Yes will do.

> @@ -365,14 +354,13 @@ static void __exception_irq_entry
> gic_handle_irq(struct pt_regs *regs)
>              smp_rmb();
>
>              /*
> -             * Samsung's funky GIC encodes the source CPU in
> -             * GICC_IAR, leading to the deactivation to fail if
> -             * not written back as is to GICC_EOI.  Stash the
> -             * INTID away for gic_eoi_irq() to write back.
> -             * This only works because we don't nest SGIs...
> +             * The GIC encodes the source CPU in GICC_IAR,
> +             * leading to the deactivation to fail if not
> +             * written back as is to GICC_EOI.  Stash the INTID
> +             * away for gic_eoi_irq() to write back.  This only
> +             * works because we don't nest SGIs...
>               */
> -            if (is_frankengic())
> -                set_sgi_intid(irqstat);
> +            this_cpu_write(sgi_intid, intid);

I assume that it should be irqstat here and not intid?

Cheers
Jon

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