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

[Abhijeet Dharmapurikar]

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. 
But shouldnt set_irq_wake() do something similar?

Do I need to request IRQF_NO_SUSPEND for all the interrupts that could 
possibly wakeup the system - seems a bit unnecessary. IMO the interrupt 
should not be disabled if it is marked IRQF_NO_SUPEND || IRQ_WAKEUP is set.

Abhijeet


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