Re: [PATCH] GIC: Assign correct flow handler type in set_type callback

[Abhijeet Dharmapurikar]

On 12/31/2010 02:39 AM, Abhijeet Dharmapurikar wrote:
> On 12/29/2010 10:27 PM, Rabin Vincent wrote:
> > On Thu, Dec 30, 2010 at 10:59 AM, Abhijeet Dharmapurikar
> > <adharmap@xxxxxxxxxxxxxx> wrote:
> > > There are some interrupts that are true edge triggered in nature. If not
> > > marked IRQ_PENDING, when disabled, they will be lost.
> > >
> > > Use the set_type callback to assign the correct flow type handler for
> > > shared peripheral interrupts.
> > >
> > > Signed-off-by: Abhijeet Dharmapurikar<adharmap@xxxxxxxxxxxxxx>
> > > ---
> > > This came to light when a edge triggered interrupt was supposed to
> > > wakeup the
> > > sytem. The flow handler was set to the default handle_level_irq. On
> > > the resume
> > > path the flow handler was invoked right after the I bit was cleared
> > > but before
> > > each individual interrupts were enabled. This made the
> > > handle_level_irq ignore
> >
> > Why does the flow handler hit when the interrupt is disabled? Have you
> > set
> > IRQF_NOSUSPEND on this interrupt?
> Since GIC doesnt have disable callback it implements lazy disabling. The
> interrupt is only marked IRQ_DISABLED in the descriptor but is not
> masked in the GIC. Hence the interrupt flow handler is hit.
>
> Now that I re-read the code setting IRQF_NO_SUSPEND would fix the issue.

Let me correct myself, IRQF_NO_SUSPEND isnt exactly what I want to do. 
If an interrupt triggers after suspend_device_irqs() is run and before 
the I bit is set in arch_suspend_disable_irqs() the system will handle 
the interrupt but will not abort suspend - check_wakeup_irqs() will 
return 0.

IMO, using handle_edge_irq() for an edge triggered wakeup interrupt 
would be the right way to address the issue.

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