Re: [RFC PATCH] genirq: set pending flag for disabled level interrupt

[Abhijeet Dharmapurikar]

On 09/02/2011 01:47 AM, Thomas Gleixner wrote:
> On Mon, 8 Aug 2011, Abhijeet Dharmapurikar wrote:
>
> > For hardware which has no wakeup source configuration facility, it needs
> > its wakeup interrupts unmasked.
> > If a wakeup edge interrupt triggered while the system was suspending the
> > edge flow handler marks it pending and masks the interrupt. The kernel
> > checks pending flag on wakeup interrupts and aborts suspend if one is set.
> >
> > If a wakeup level interrupt triggered while the system was suspending the
> > level flow handler masks the interrupt without setting the pending flag.
> > Suspend won't be aborted. This is fine as it is expected that a level
> > triggered interrupt will stay triggered and cause the system to resume.
> > This however doesn't work on chips that don't have wakeup configuration
> > in hardware because such chips need that interrupt unmasked for causing
> > a resume.
> >
> > Address that shortcoming by making the level flow handler set the pending
> > flag if a wakeup interrupt controlled by such a chip is triggered while
> > it is suspended.
>
> And how is that supposed to work ?
>
> check_irq_resend()
> {
>          if (irq_settings_is_level(desc))
>                  return;
> ...

Hmm, I missed this check. Sorry.

I will send another patch that extends check_wakeup_irqs().

> > Signed-off-by: Abhijeet Dharmapurikar<adharmap@xxxxxxxxxxxxxx>
> > ---
> > If a level interrupt irq triggered right while the system was doing
> > suspend_noirqs, the level flow handler will mask that interrupt and when the
> > system went in to power collapse the interrupt controller did not wakeup the
> > phone. The interrupt controller needs an interrupt triggered and masked to
> > wakeup the phone - it does not have any wakeup interrupt configuration.
> > The solution presented here is to mark that level triggered
> > wakeup interrupt pending for chips with IRQCHIP_MASK_ON_SUSPEND. This will cause
> > check_wakeup_irqs to abort suspend.
> > Other solution would be to unmask such level interrupt in check_wakeup_irqs()
> > but that seemed like I was expanding and complicating check_wakeup_irqs()
> > duties - let me know if you think otherwise.
> > Note that we cannot unmask the interrupt in the level flow handler, that will
> > cause an interrupt storm.
> >
> >   include/linux/irq.h |    4 +++-
> >   kernel/irq/chip.c   |   16 +++++++++++++++-
> >   2 files changed, 18 insertions(+), 2 deletions(-)


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