[BUG] irqchip: armada-370-xp: workqueue lockup

[Steffen Trumtrar]

Marc Zyngier <maz at kernel.org> writes:

> On Wed, 22 Sep 2021 07:49:05 +0100,
> Steffen Trumtrar <s.trumtrar at pengutronix.de> wrote:
>>
>>
>> Hi,
>>
>> Marc Zyngier <maz at kernel.org> writes:
>> > It isn't obvious to me how reverting this patch fixes anything.  The
>> > fasteoi flow does the same thing as far as the IPI driver is concerned
>> >
>>
>> didn't the fasteoi flow just call the irq_eoi earlier? Same as the
>> irq_ack now?
>
> Yes, of course, you are correct. Another proof that the whole initial
> fasteoi flow that used EOI as an ACK was *a bad idea* (tm).
>
>>
>> >
>> > However, it appears that I have broken that part much earlier in
>> > f02147dd02eb ("irqchip/armada-370-xp: Configure IPIs as standard
>> > interrupts"), as the write to ARMADA_370_XP_IN_DRBEL_CAUSE_OFFS that
>> > used to occur before the handling (an ACK) has now been moved after as
>> > an EOI. That's a pretty good way to lose edge interrupts.
>> >
>> > Could you try the following patch on top of 5.12-rc2?
>> >
>> > Thanks,
>> >
>> > 	M.
>> >
>> > diff --git a/drivers/irqchip/irq-armada-370-xp.c b/drivers/irqchip/irq-armada-370-xp.c
>> > index 7557ab551295..53e0fb0562c1 100644
>> > --- a/drivers/irqchip/irq-armada-370-xp.c
>> > +++ b/drivers/irqchip/irq-armada-370-xp.c
>> > @@ -359,16 +359,16 @@ static void armada_370_xp_ipi_send_mask(struct irq_data *d,
>> >  		ARMADA_370_XP_SW_TRIG_INT_OFFS);
>> >  }
>> >
>> > -static void armada_370_xp_ipi_eoi(struct irq_data *d)
>> > +static void armada_370_xp_ipi_ack(struct irq_data *d)
>> >  {
>> >  	writel(~BIT(d->hwirq), per_cpu_int_base + ARMADA_370_XP_IN_DRBEL_CAUSE_OFFS);
>> >  }
>> >
>> >  static struct irq_chip ipi_irqchip = {
>> >  	.name		= "IPI",
>> > +	.irq_ack	= armada_370_xp_ipi_ack,
>> >  	.irq_mask	= armada_370_xp_ipi_mask,
>> >  	.irq_unmask	= armada_370_xp_ipi_unmask,
>> > -	.irq_eoi	= armada_370_xp_ipi_eoi,
>> >  	.ipi_send_mask	= armada_370_xp_ipi_send_mask,
>> >  };
>>
>> This fixes it, yes \o/
>
> Thanks. Can I use this as a Tested-by: tag in the official patch?
>

Yes, of course. Go ahead.


Thanks,
Steffen

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