[PATCH 0/5] Fix regression introduced by set_irq_flags() removal

Thomas Petazzoni
2017-02-24T16:56:50Z

Thomas,

On Tue, 8 Dec 2015 11:54:11 +0100 (CET), Thomas Gleixner wrote:
> On Tue, 8 Dec 2015, Thomas Petazzoni wrote:
> > When a device driver uses a normal (non per-CPU) interrupt, then it
> > doesn't have to take care of disabling the interrupt on suspend and
> > re-enabling the interrupt on resume at the interrupt controller level.
> > This is all transparently handled by the irqchip driver.
> >
> > Why should the handling of per-CPU interrupts be different and require
> > explicit handling from each device driver rather than being
> > transparently handled by the irqchip driver ?
>
> Fair enough. Did not think about the boot cpu part.

I am reviving this *very* old thread, as I wanted to push the remaining
patches. But it seems like the issue no longer exists.

Summary of the story:

- Between 4.2 and 4.3-rc, commit d17cab4451df1 broke suspend/resume on
Armada XP. The issue was that the IRQ_NOAUTOEN was no longer
cleared, and therefore irqd_irq_disabled() no longer indicated that
our per-CPU interrupts were enabled, and consequently our local
timer per-CPU interrupt was not re-enabled upon resume.

- After some discussion, we merged a very simple workaround for 4.3,
which consists in clearing IRQ_NOAUTOEN:

irq_clear_status_flags(virq, IRQ_NOAUTOEN);

But the idea was to do a better implementation later on, which my
patch series at the same time was trying.

- Now, fast forward to 4.10, if I remove the:

irq_clear_status_flags(virq, IRQ_NOAUTOEN);

then I can no longer reproduce the original issue from 4.3-rc, which
clearing IRQ_NOAUTOEN was fixing. My system resumes fine.

Has there been some changes in this area that could explain that
irqd_irq_disable() now indicates that my per-CPU interrupt is enabled,
while it didn't say so back in 4.3-rc ?

Thanks,

Thomas
--
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux and Kernel engineering