Messages in this thread | | | Date | Wed, 15 Jan 2020 15:22:23 +0000 | From | Marc Zyngier <> | Subject | Re: [PATCH] irqchip: mips-cpu: Remove eoi operation |
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On 2020-01-15 14:23, Jiaxun Yang wrote: > 于 2020年1月15日 GMT+08:00 下午9:40:31, Marc Zyngier <maz@kernel.org> 写到: >> On 2020-01-14 23:30, Paul Burton wrote: >>> Hi Jiaxun, >>> >>> On Mon, Jan 13, 2020 at 06:12:51PM +0800, Jiaxun Yang wrote: >>>> The eoi opreation in mips_cpu_irq_controller caused >> chained_irq_enter >>>> falsely consider CPU IP interrupt as a FastEOI type IRQ. So the >>>> interrupt >>>> won't be masked during in handler. Which might lead to spurious >>>> interrupt. >>>> >>>> Thus we simply remove eoi operation for mips_cpu_irq_controller, >>>> >>>> Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com> >>>> --- >>>> drivers/irqchip/irq-mips-cpu.c | 1 - >>>> 1 file changed, 1 deletion(-) >>>> >>>> diff --git a/drivers/irqchip/irq-mips-cpu.c >>>> b/drivers/irqchip/irq-mips-cpu.c >>>> index 95d4fd8f7a96..0ad7f1f9a58b 100644 >>>> --- a/drivers/irqchip/irq-mips-cpu.c >>>> +++ b/drivers/irqchip/irq-mips-cpu.c >>>> @@ -55,7 +55,6 @@ static struct irq_chip mips_cpu_irq_controller = { >>>> .irq_mask = mask_mips_irq, >>>> .irq_mask_ack = mask_mips_irq, >>>> .irq_unmask = unmask_mips_irq, >>>> - .irq_eoi = unmask_mips_irq, >>>> .irq_disable = mask_mips_irq, >>>> .irq_enable = unmask_mips_irq, >>>> }; >>> >>> This one scares me; something doesn't seem right. The irq_eoi (née >> eoi) >>> callback was first added way back in commit 1417836e81c0 ("[MIPS] use >>> generic_handle_irq, handle_level_irq, handle_percpu_irq"). The commit >>> message there states that the motivation was to allow use of >>> handle_percpu_irq(), and indeed handle_percpu_irq() does: >>> >>> irq_ack() (ie. mask) >>> invoke the handler(s) >>> irq_eoi() (ie. unmask) >>> >>> By removing the irq_eoi callback I don't see how we'd ever unmask the >>> interrupt again..? >> >> To be completely blunt, the fact that unmask and eoi are implemented >> the >> same way is a clear sign that this is a bit broken. >> >> irq_eoi is used if the irqchip tracks the IRQ life-cycle in HW, and >> it's >> not obvious that this is the case. The fact that ack is also mapped to >> mask > > It's just a kind of hack to workaround the fact that our current > percpu irq handler assumed > all percpu irqs are edge triggered or fasteoi type. > > However MIPS processor implemented it in level triggered way. > > My solution would be add a check. If neither ack nor eoi exist for the > chip, > than we assume it's level triggered and process precpu irq in > mask/unmask way. > > Could it be a possible option?
Post the patch, and we'll discuss it.
Thanks,
M. -- Jazz is not dead. It just smells funny...
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