Re: [Qualcomm PM8921 MFD v2 2/6] mfd: pm8xxx: Add irq support

[Abhijeet Dharmapurikar <adharmap@codeaurora.org>]

Thomas Gleixner wrote:
> On Fri, 11 Mar 2011, Abhijeet Dharmapurikar wrote:
>>>> Yes however while updating the code I noticed that I would need to keep
>>>> account of all the interrupts enabled and all the interrupts marked
>>>> wakeup.
>>>> This aids in switching to the wakeup set in the suspend callback and the
>>>> enabled set in the resume callback. I will update the resume callback to
>>>> enable the interrupts in irqs_allowed(the local state storage) in the next
>>>> patch (my current patch does not do that).
>>>>
>>>> IOW I need to keep the local state storage.
>>> Wrong. The interrupts are disabled and reenabled by the core code and
>>> not by some extra suspend/resume callbacks in your driver. The core
>>> checks those marked as IRQ_WAKE, the wake callback to the irq chip is
>>> only there if you need to set up some hardware register in order to
>>> make the wake functionality work. So again, you don't need local state
>>> as the core tracks the state for you.
>> Help me understand this, the core code calls disable on all the interrupts
>> while going to suspend. Notice that I have no disable callback, which means
>> those interrupts remain unmasked.
>>
>> The genirq code does not mask the interrupt while going to suspend, it only
>> calls disable(), which I understand should not mask the interrupt for
>> check_wakeup_irqs() to work.
>>
>> If I don't mask that accelerometer interrupts in the interrupt controller's
>> suspend() the phone will wakeup every time the user moves around, draining the
>> battery unnecessarily.
> 
> That's why we mark the interrupts which can wake up from suspend with
> set_wake() so you can configure your hardware accordingly. That's how
> all other stuff works, at least how it's supposed to work. 
> 
> If there is no way to tell the interrupt controller which interrupts
> are wakeup sources and which are not, then working around it with
> local state and private suspend/resume functions is the WRONG answer.
> 
> Simply because this kind of misdesigned hardware will creep up over
> and over and we want to handle these cases in the core. Even for a
> sinlge instance like yours solving it in the core is the right thing
> to do, because it's a ~3 lines patch to the core code to get this
> done.

~3 lines patch to the code sounds promising. Please tell me how?


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