linux-kernel - Re: [PATCH RESEND] rtc: da9063: add as wakeup source

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Date:   Fri, 19 Nov 2021 12:07:10 +0300
From:   Nikita Shubin <nikita.shubin@...uefel.me>
To:     Alexandre Belloni <alexandre.belloni@...tlin.com>
Cc:     David Abdurachmanov <david.abdurachmanov@...ive.com>,
        Support Opensource <support.opensource@...semi.com>,
        Alessandro Zummo <a.zummo@...ertech.it>,
        linux-rtc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RESEND] rtc: da9063: add as wakeup source

Hello Alexandre,

Sorry for the rush - I should have to think more before sending this
patch ...

On Thu, 18 Nov 2021 10:33:34 +0100
Alexandre Belloni <alexandre.belloni@...tlin.com> wrote:

> Hello,
> 
> On 18/11/2021 11:40:08+0300, Nikita Shubin wrote:
> > in case if threaded irq registered successfully - add da9063
> > as a wakeup source if "wakeup-source" node present in device tree,
> > set as wakeup capable otherwise.
> > 
> > Signed-off-by: Nikita Shubin <nikita.shubin@...uefel.me>
> > ---
> >  drivers/rtc/rtc-da9063.c | 10 +++++++++-
> >  1 file changed, 9 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/rtc/rtc-da9063.c b/drivers/rtc/rtc-da9063.c
> > index d4b72a9fa2ba..1aceb5ba6992 100644
> > --- a/drivers/rtc/rtc-da9063.c
> > +++ b/drivers/rtc/rtc-da9063.c
> > @@ -490,7 +490,15 @@ static int da9063_rtc_probe(struct
> > platform_device *pdev) da9063_alarm_event,
> >  					IRQF_TRIGGER_LOW |
> > IRQF_ONESHOT, "ALARM", rtc);
> > -	if (ret)
> > +	if (!ret) {
> > +		if (device_property_present(&pdev->dev,
> > "wakeup-source")) {
> > +			device_init_wakeup(&pdev->dev, true);  
> 
> If wakeup-source is present, then this should be done regardless of
> the registration of the interrupt handler. Note that wakeup-source and
> interrupt are supposed to be mutually exclusive.
> 

We still able to wakeup either ALARM IRQ is present or not.

Actually the only thing is needed in this particular case is the ability
to set "wakealarm" via sysfs - so we can wakeup from
POWER-DOWN/DELIVERY/RTC modes, namely shutdown, regardless of CONFIG_PM.

Setting dev->power.can_wakeup to true is enough for that.

On the other hand device_init_wakeup also sets can_wakeup.

May be it's enough to use device_init_wakeup in case if ALARM IRQ is
present or "wakeup-source" is set ?

I see some construction in drivers/rtc like :

```
rtc/rtc-pcf2127.c:673:  if (alarm_irq > 0 ||
device_property_read_bool(dev, "wakeup-source")) {
rtc/rtc-ab-eoz9.c:552:  if (client->irq > 0 ||
device_property_read_bool(dev, "wakeup-source")) {
```




> > +			dev_info(&pdev->dev, "registered as wakeup
> > source.\n");  
> 
> This is too verbose please avoid adding new strings
> 
> > +		} else {
> > +			device_set_wakeup_capable(&pdev->dev,
> > true);  
> 
> I think this is misusing the wakeup-source property for configuration
> that should be left to userspace.
> 
> > +			dev_info(&pdev->dev, "marked as wakeup
> > capable.\n");  
> 
> Ditto
> 
> > +		}
> > +	} else  
> 
> unbalanced brackets
> 
> 
> >  		dev_err(&pdev->dev, "Failed to request ALARM IRQ
> > %d: %d\n", irq_alarm, ret);
> >  
> > -- 
> > 2.31.1
> >   
>