Re: [PATCH] rtc: rtc-pm8xxx: control default alarm wake up capability

[Anvesh Jain P]

On 8/3/2023 7:10 PM, Alexandre Belloni wrote:
> On 03/08/2023 15:39:41+0200, Alexandre Belloni wrote:
> > On 03/08/2023 19:01:51+0530, Anvesh Jain P wrote:
> > > On 8/2/2023 1:04 AM, Alexandre Belloni wrote:
> > > > On 01/08/2023 18:18:46+0530, Anvesh Jain P wrote:
> > > > > In automotive systems, RTC should not wake up the device when it is parked
> > > > > or when it is garage to avoid leakage current. providing a control from
> > > > > device tree to avoid RTC wake up based on the use case is reason for this
> > > > > patch.
> > > >
> > > > Then simply avoid providing an IRQ or setting an alarm.
> > > The purpose of the change is just to block alarms/notifications waking up
> > > the target when it is in Suspend2ram(low power) mode.
> > > if we disable IRQ, alarms/notifications won't come even when the target is
> > > in active mode.
> > > This change will just stop the wake up capability of the alarm when target
> > > is in suspend 2 ram mode based on flag passed from device tree.
> > > Use case of this patch is,
> > > In mobile targets where alarms / notifications will need to wake up the
> > > target when there is a reminder as per user expectation.
> > > where as in automotive targets, when driver is not in Car and target is in
> > > suspend state, alarms/notifications would have no meaning and waking up the
> > > target of no use as there is no user to attend the message. hence blocking
> > > them in automotive use cases based on device tree is the use of this patch.
> >
> > Simply remove the alarm before going to suspend, this is a userspace
> > policy, it has nothing to do in the device or kernel.
> s/device/device tree/ obviously.
How to remove from userspace?, if we remove all alarms from userspace, 
will the alarms expiring after wake up would be restored while target 
resumes from suspend 2 ram?
The change would not change alarms behavior. it blocks all notifications 
causing wake up if "disable-alarm-wakeup" property defined in device 
tree. if it is not defined, current behavior of alarm won't change.
> > > > > On 8/1/2023 6:10 PM, Alexandre Belloni wrote:
> > > > > > On 01/08/2023 17:15:49+0530, Anvesh Jain P wrote:
> > > > > > > Enable & disable rtc alarm wake up capability based on
> > > > > > > default parameter passed from device tree.
> > > > > >
> > > > > > I see what you are doing but not why this is necessary, NAK.
> > > > > >
> > > > > > > Signed-off-by: Venkata Rao Kakani <quic_vkakani@xxxxxxxxxxx>
> > > > > > > Signed-off-by: Anvesh Jain P <quic_ajainp@xxxxxxxxxxx>
> > > > > > > ---
> > > > > > >     drivers/rtc/rtc-pm8xxx.c | 3 +++
> > > > > > >     1 file changed, 3 insertions(+)
> > > > > > >
> > > > > > > diff --git a/drivers/rtc/rtc-pm8xxx.c b/drivers/rtc/rtc-pm8xxx.c
> > > > > > > index f6b779c12ca7..bed57be602b6 100644
> > > > > > > --- a/drivers/rtc/rtc-pm8xxx.c
> > > > > > > +++ b/drivers/rtc/rtc-pm8xxx.c
> > > > > > > @@ -523,6 +523,9 @@ static int pm8xxx_rtc_probe(struct platform_device *pdev)
> > > > > > >     	if (rc)
> > > > > > >     		return rc;
> > > > > > > +	if (of_property_read_bool(pdev->dev.of_node, "disable-alarm-wakeup"))
> > > > > > > +		device_set_wakeup_capable(&pdev->dev, false);
> > > > > > > +
> > > > > > >     	rc = dev_pm_set_wake_irq(&pdev->dev, rtc_dd->alarm_irq);
> > > > > > >     	if (rc)
> > > > > > >     		return rc;
> > > > > > >
> > > > > > > base-commit: 0a8db05b571ad5b8d5c8774a004c0424260a90bd
> > > > > > > --
> > > > > > > 2.17.1
> >
> > --
> > Alexandre Belloni, co-owner and COO, Bootlin
> > Embedded Linux and Kernel engineering
> > https://bootlin.com