linux-kernel - Re: [irqchip: irq/irqchip-next] irqchip/bcm2836: Fix IPI acknowledgement after conversion to handle_percpu_devid

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Date:   Fri, 18 Dec 2020 20:53:53 +0000
From:   Marc Zyngier <maz@...nel.org>
To:     Valentin Schneider <valentin.schneider@....com>
Cc:     linux-kernel@...r.kernel.org, Guenter Roeck <linux@...ck-us.net>,
        tglx@...utronix.de
Subject: Re: [irqchip: irq/irqchip-next] irqchip/bcm2836: Fix IPI
 acknowledgement after conversion to handle_percpu_devid_irq

On 2020-12-18 20:36, Valentin Schneider wrote:
> On 18/12/20 18:40, irqchip-bot for Marc Zyngier wrote:
>> The following commit has been merged into the irq/irqchip-next branch 
>> of irqchip:
>> 
>> Commit-ID:     d7f39c40ebb6986e7371510d1c20a4efee4a7f0d
>> Gitweb:        
>> https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms/d7f39c40ebb6986e7371510d1c20a4efee4a7f0d
>> Author:        Marc Zyngier <maz@...nel.org>
>> AuthorDate:    Fri, 18 Dec 2020 18:03:46
>> Committer:     Marc Zyngier <maz@...nel.org>
>> CommitterDate: Fri, 18 Dec 2020 18:34:17
>> 
>> irqchip/bcm2836: Fix IPI acknowledgement after conversion to 
>> handle_percpu_devid_irq
>> 
>> It appears that despite its name, the bcm2836_arm_irqchip_ipi_eoi()
>> callback is an acknowledgement, and not an EOI. This means that
>> we lose IPIs that are made pending between the handling of the
>> IPI and the write to LOCAL_MAILBOX0_CLR0. With the right timing,
>> things fail nicely.
>> 
>> This used to work with handle_percpu_devid_fasteoi_ipi(), which
>> started by eoi-ing the interrupt. With the standard fasteoi flow,
>> this doesn't work anymore.
>> 
>> So let's use this callback for what it is, an ack. Your favourite
>> RPi-2/3 is back up and running.
>> 
> 
> Thanks for cleaning up my mess!

Shared responsibilities... ;-)

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