On Thursday 19 July 2018 06:06 PM, Johan Hovold wrote: > On Thu, Jul 19, 2018 at 05:52:17PM +0530, Keerthy wrote: >> On Thursday 19 July 2018 05:23 PM, Keerthy wrote: >>> On Thursday 19 July 2018 03:32 PM, Johan Hovold wrote: >>>> On Thu, Jul 12, 2018 at 10:37:37AM +0530, Keerthy wrote: > >>>>> @@ -470,6 +476,9 @@ static void omap_rtc_power_off(void) >>>>> val = rtc_read(rtc, OMAP_RTC_INTERRUPTS_REG); >>>>> rtc_writel(rtc, OMAP_RTC_INTERRUPTS_REG, >>>>> val | OMAP_RTC_INTERRUPTS_IT_ALARM2); > >>>>> + /* Our calculations started right before the rollover, try again */ > >>>>> + if (seconds != rtc_read(omap_rtc_power_off_rtc, OMAP_RTC_SECONDS_REG)) >>>>> + goto again; >>>> >>>> Here the alarm may have gone off as part of the roll over, in which case >>>> you shouldn't retry. >>> >>> Ex: We programmed at Sec = 2 and we expect ALARM2 to fire at sec = 3. >>> >>> In the event of Roll over before setting the >>> OMAP_RTC_INTERRUPTS_IT_ALARM2 bit in the OMAP_RTC_INTERRUPTS_REG will we >>> not miss the ALARM2 event? Then poweroff would fail right? > > Right, that would fail. > >>> Hence the attempt to retry the next second. This sequence would begin >>> right at the beginning of a new second and we expect the full sequence >>> to get over without having to retry again. >>> >>> Hope i am clear. > > Yes, sure, but my point is that could end up retrying also after the > alarm has fired correctly (e.g. due to latencies in turning of the > power)> > It may be enough to check OMAP_RTC_STATUS_REG before retrying. Ah okay. Yes this makes sense. I will use the status to retry. > >> I tried to program the interrupt for the same second on the hardware and >> it does not fire. So to take care of roll over corner case one attempt >> to retry is needed. > > Yes, that's expected. > > Thanks, > Johan >
