Messages in this thread | | | Date | Wed, 15 Jan 2020 13:40:31 +0000 | From | Marc Zyngier <> | Subject | Re: [PATCH] irqchip: mips-cpu: Remove eoi operation |
| |
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 just adds to my feeling...
M. -- Jazz is not dead. It just smells funny...
| |