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SubjectRe: [PATCH] rtc: zynqmp: Clear alarm interrupt status before interrupt enable
On 10/02/2020 12:48:14+0100, Michal Simek wrote:
> Hi,
>
> čt 12. 12. 2019 v 14:01 odesílatel Srinivas Neeli
> <srinivas.neeli@xilinx.com> napsal:
> >
> > Fix multiple occurring interrupts for alarm interrupt. RTC module doesn't
> > clear the alarm interrupt status bit immediately after the interrupt is
> > triggered.This is due to the sticky nature of the alarm interrupt status
> > register. The alarm interrupt status register can be cleared only after
> > the second counter outruns the set alarm value. To fix multiple spurious
> > interrupts, disable alarm interrupt in the handler and clear the status
> > bit before enabling the alarm interrupt.
> >
> > Fixes: 11143c19eb57 ("rtc: add xilinx zynqmp rtc driver")
> > Signed-off-by: Srinivas Neeli <srinivas.neeli@xilinx.com>
> > ---
> > drivers/rtc/rtc-zynqmp.c | 29 ++++++++++++++++++++++++-----
> > 1 file changed, 24 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/rtc/rtc-zynqmp.c b/drivers/rtc/rtc-zynqmp.c
> > index 5786866c09e9..d311e3ef1f21 100644
> > --- a/drivers/rtc/rtc-zynqmp.c
> > +++ b/drivers/rtc/rtc-zynqmp.c
> > @@ -38,6 +38,8 @@
> >
> > #define RTC_CALIB_DEF 0x198233
> > #define RTC_CALIB_MASK 0x1FFFFF
> > +#define RTC_ALRM_MASK BIT(1)
> > +#define RTC_MSEC 1000
> >
> > struct xlnx_rtc_dev {
> > struct rtc_device *rtc;
> > @@ -124,11 +126,28 @@ static int xlnx_rtc_alarm_irq_enable(struct device *dev, u32 enabled)
> > {
> > struct xlnx_rtc_dev *xrtcdev = dev_get_drvdata(dev);
> >
>
> here shouldn't be empty line.
>
> > - if (enabled)
> > + unsigned int status;
> > + ulong timeout;
> > +
> > + timeout = jiffies + msecs_to_jiffies(RTC_MSEC);
> > +
> > + if (enabled) {
> > + while (1) {
> > + status = readl(xrtcdev->reg_base + RTC_INT_STS);
> > + if (!((status & RTC_ALRM_MASK) == RTC_ALRM_MASK))
> > + break;
> > +
> > + if (time_after_eq(jiffies, timeout)) {
> > + dev_err(dev, "Time out occur, while clearing alarm status bit\n");
> > + return -ETIMEDOUT;
> > + }
> > + writel(RTC_INT_ALRM, xrtcdev->reg_base + RTC_INT_STS);
> > + }
> > +
> > writel(RTC_INT_ALRM, xrtcdev->reg_base + RTC_INT_EN);
> > - else
> > + } else {
> > writel(RTC_INT_ALRM, xrtcdev->reg_base + RTC_INT_DIS);
> > -
> > + }
>
> And here it was good to have empty line.
>
> > return 0;
> > }
> >
> > @@ -183,8 +202,8 @@ static irqreturn_t xlnx_rtc_interrupt(int irq, void *id)
> > if (!(status & (RTC_INT_SEC | RTC_INT_ALRM)))
> > return IRQ_NONE;
> >
> > - /* Clear RTC_INT_ALRM interrupt only */
> > - writel(RTC_INT_ALRM, xrtcdev->reg_base + RTC_INT_STS);
> > + /* Disable RTC_INT_ALRM interrupt only */
> > + writel(RTC_INT_ALRM, xrtcdev->reg_base + RTC_INT_DIS);
> >
> > if (status & RTC_INT_ALRM)
> > rtc_update_irq(xrtcdev->rtc, 1, RTC_IRQF | RTC_AF);
> > --
> > 2.7.4
>
> Other then these two above things look good.
>
> Alexandre: Any issue with this patch?
>

No issue, I was kind of waiting for your review. I'll take the patch
once your comments are addressed.

--
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

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