linux-kernel - Re: [PATCH 1/2] irqchip/gic: Handle non-standard SGI deactivation on Samsung's Franken-GIC

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Date:   Tue, 15 Sep 2020 15:52:15 +0100
From:   Marc Zyngier <maz@...nel.org>
To:     Marek Szyprowski <m.szyprowski@...sung.com>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>, kernel-team@...roid.com
Subject: Re: [PATCH 1/2] irqchip/gic: Handle non-standard SGI deactivation on
 Samsung's Franken-GIC

On 2020-09-15 15:06, Marek Szyprowski wrote:
> On 15.09.2020 15:39, Marc Zyngier wrote:
>> The GIC available on some of Samsung's A9-based platform is
>> thankfully one of a kind. On top of not presenting a banked
>> programing model (each CPU has its own base addresses for both
>> distributor and CPU interface), it also encodes the source CPU
>> for SGIs in the INTID read from IAR, and requires this exact
>> value to be written back to EOI.
>> 
>> Without this, interrupts are never deactivated, and the kernel
>> grinds to a halt.
>> 
>> Work around it by stashing the INTID for in-flight SGIs, and
>> using that value on EOI. This only works because we don't nest
>> SGIs.
>> 
>> Reported-by: Marek Szyprowski <m.szyprowski@...sung.com>
>> Fixes: ac063232d4b0 ("irqchip/gic: Configure SGIs as standard 
>> interrupts")
>> Signed-off-by: Marc Zyngier <maz@...nel.org>
> 
> Works fine, thanks!
> 
> Tested-by: Marek Szyprowski <m.szyprowski@...sung.com>

Thanks for having reported the failure, and your patience with testing
all kind of random things! ;-)

         M.
-- 
Jazz is not dead. It just smells funny...