[rtc-linux] Re: [PATCH v3 7/8] rtc: ds3232-core: fix issue when irq is shared several devices

[Alexandre Belloni <alexandre.belloni@free-electrons.com>]

On 03/03/2016 at 23:10:35 +0900, Akinobu Mita wrote :
> 2016-03-01 0:13 GMT+09:00 Akinobu Mita <akinobu.mita@gmail.com>:
> > ds3232-core requests irq with IRQF_SHARED, so irq can be shared by
> > several devices.  But the irq handler for ds3232 unconditionally
> > disables the irq at first and the irq is re-enabled only when the
> > interrupt source was the ds3232's alarm.  This behaviour breaks the
> > devices sharing the same irq in the various scenarios.
> >
> > Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
> > Cc: Alessandro Zummo <a.zummo@towertech.it>
> > Cc: Alexandre Belloni <alexandre.belloni@free-electrons.com>
> > Cc: Dennis Aberilla <denzzzhome@yahoo.com>
> > ---
> > * New patch from this version
> >
> >  drivers/rtc/rtc-ds3232-core.c | 14 ++------------
> >  1 file changed, 2 insertions(+), 12 deletions(-)
> >
> > diff --git a/drivers/rtc/rtc-ds3232-core.c b/drivers/rtc/rtc-ds3232-core.c
> > index be8dfe0..6489380 100644
> > --- a/drivers/rtc/rtc-ds3232-core.c
> > +++ b/drivers/rtc/rtc-ds3232-core.c
> > @@ -59,7 +59,6 @@ struct ds3232 {
> >          */
> >         struct mutex mutex;
> >         bool suspended;
> > -       int exiting;
> >  };
> >
> >  static int ds3232_check_rtc_status(struct device *dev)
> > @@ -314,8 +313,6 @@ static irqreturn_t ds3232_irq(int irq, void *dev_id)
> >         struct device *dev = dev_id;
> >         struct ds3232 *ds3232 = dev_get_drvdata(dev);
> >
> > -       disable_irq_nosync(irq);
> > -
> >         /*
> >          * If rtc as a wakeup source, can't schedule the work
> >          * at system resume flow, because at this time the i2c bus
> 
> I found that this patch is not correct because interrupt is re-enabled
> after this hardirq handler finished without clearing Alarm Flag or
> Alarm Interrupt Enable in RTC register.
> 
> Maybe we should drop IRQF_SHARED flag.

I think the best is to completely reworke the irq handling. It dates
from many many year ago and can be replace by a simple threaded irq.
This will solve your issue.


-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

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