Re: [patch]GPIO button is supposed to wake the system up if the wakeup attribute is set

["Li, Aubrey" <aubrey.li@linux.intel.com>]

On 2014/4/18 7:54, Dmitry Torokhov wrote:
> Hi Aubrey,
> 
> On Fri, Apr 18, 2014 at 12:42:24AM +0800, Li, Aubrey wrote:
>> On 2014/4/16 20:35, Laxman Dewangan wrote:
>>> On Tuesday 15 April 2014 09:48 PM, Li, Aubrey wrote:
>>>> On 2014/4/15 20:38, Laxman Dewangan wrote:
>>>>> On Monday 14 April 2014 09:12 PM, Li, Aubrey wrote:
>>>>>> ping...
>>>>>>
>>>>>> On 2014/4/10 18:48, One Thousand Gnomes wrote:
>>>>>>>
>>>>> I think when we say irq_wake_enable() then based on underlying HW, it
>>>>> should not turn off the irq if it is require for the wakeup. I mean it
>>>>> need to be handle in the hw specific callbacks to keep enabling the
>>>>> wakeup irq on suspend also.
>>>> I failed to see why this can't be generic to all of the GPIO buttons for
>>>> suspend wakeup. Do you see any cases broken by this proposal?
>>>
>>> My point here is that if underlying HW needs to have irq enabled for
>>> wakup then it need to handle in centralized location i.e. the driver
>>> which is implementing it for the irq callbacks.
>>> Otherwise, we need to change this on multiple places who needs wakeups
>>> which is vast in nature like sd driver for sdcard insert/remove etc.
>>> almost all drivers which need wakeups through GPIOs.
>>
>> I think we have to handle this driver by driver. I didn't see how can we
>> make it in a centralized location. Looking forward to see your proposal.
>>
>>>
>>>>> For me, I have key which is interrupt based from PMIC, not based on GPIO
>>>>> and on that if I set it to IRQF_EARLY_RESUME then it works fine.
>>>>>
>>>> IRQF_NO_SUSPEND - Do not disable this IRQ during suspend
>>>> IRQF_EARLY_RESUME - Resume IRQ early during syscore instead of at device
>>>> resume time.
>>>>
>>>> IRQF_NO_SUSPEND is exactly what I want, instead of IRQF_EARLY_RESUME.
>>>> Can you please send your proposal/code to help me understand why this
>>>> has to hw specific and why IRQF_EARLY_RESUME is better than
>>>> IRQF_NO_SUSPEND?
>>>
>>> IRQF_EARLY_RESUME helps to re-enable mask or irq before parent interrupt
>>> resume and so parent isr handler sees the irq flag enabled when it try
>>> to scan source of interrupt. Otherwise parent isr handler treat this as
>>> spurious interrupt and does not call handler as irq flag disabled for that.
>>>
>>> This only happen when on resume, parent inettrupt enabled before the
>>> child interrupt on irq resume. Because as soon as parent isr re-enabled
>>> on resume, its hadnler get called before actually child interrupt
>>> enabled. This is what I observed mainly on PMIC and its sub irq. Not
>>> observed on SoC level of interrupts.
>>>
>>
>> This is expected behavior. I think I still need IRQF_NO_SUSPEND here.
>> What I want is, this IRQ is able to generate pm wakeup event to wake the
>> system up. It's enough for my case.
> 
> The driver does call enable_irq_wake() in its suspend routine to prepare
> the interrupt in question to be used as a wakeup source. Why isn't it
> enough? It seems to me that your platform code should properly handle
> this case instead of relying on the driver to modify IRQ flags.

Yes, gpio_keys_suspend() does call enable_irq_wake() to enable the irq
of the button. So when the button is pressed, hardware interrupt from
this irq does occur.

However, after gpio_keys_suspend(), irq_desc of this irq will be
disabled if there is no IRQF_NO_SUSPEND flag. So when the hardware
interrupt occurs, the irq handler won't call the action of the irq desc.
That is, for this case, even if the driver call enable_irq_wake() during
suspend, the irq handler in this driver won't be called because it's an
action handler, not a irq handler.

Does this make sense?

Thanks,
-Aubrey