On Fri, Jul 20, 2018 at 04:03:20PM +0530, Keerthy wrote: > > > On Thursday 19 July 2018 06:16 PM, Keerthy wrote: > > > > > > 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. > > On a second thought. Status gets set only after the next second. > > if ALARM2 status bit is set that surely means interrupt has fired but if > it is not set then there are 2 possibilities > > 1) ALARM2 is missed as the roll over happened > 2) ALARM2 yet to fire as we are yet to get to the next second. > > On the other hand Seconds gives me clear indication if we missed the > interrupt or we are about to get one. Yes, you still have to check seconds *before* retrying based on status. That should do, right? Johan -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
