On Tue, Jul 18, 2017 at 3:22 PM, Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote: > On Tue, 18 Jul 2017, dbasehore . wrote: >> On Tue, Jul 18, 2017 at 2:53 PM, Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote: >> > On Tue, 18 Jul 2017, dbasehore . wrote: >> >> On Mon, Jul 17, 2017 at 11:40 PM, Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote: >> >> > On Mon, 17 Jul 2017, dbasehore . wrote: >> >> >> On Mon, Jul 17, 2017 at 6:33 PM, Rafael J. Wysocki <rafael@xxxxxxxxxx> wrote: >> >> >> I could make a patch to try it out. I would probably add a flag to rtc >> >> >> timers to indicate whether it wakes the system (default true). We >> >> >> would have to add a sync with the rtc irq and the rtc irqwork. I would >> >> >> probably add a rtc_timer_sync function that would flush the rtc irq >> >> >> and flush the irqwork. I would call this after the freeze_ops sync >> >> >> function since the sci irq needs to finish before syncing with the rtc >> >> >> irq. Also, pm_wakeup_irq seems racy with the current implementation of >> >> >> s2idle_loop since the RTC irq could be mistakenly set as pm_wakeup_irq >> >> >> when something else actually triggered the full wakeup. Fortunately, I >> >> >> don't think pm_wakeup_irq is used for anything except debugging, but >> >> >> we might change that. >> >> > >> >> > There is another option which you might consider. We can reserve one of the >> >> > HPET comparators for that purpose and have a special interrupt handler for >> >> > it. Checking the HPET for expiry from the low level code should be trivial. >> >> > >> >> Does that handle setting up new timers properly or does the timer sync >> >> code still need to be written? >> > >> > Sorry, I don't understand the question. What is timer sync code? >> > >> >> Does the comparator allow you to have a completely separate alarm set >> in the hardware? If there's another timer setup (say some user >> specified wake alarm), we need to program that alarm after the current >> one goes off if we aren't able to program multiple alarms at the same >> time. > > The HPET consists of several independent comparator units. The kernel uses > only a limited set of them. We can reserve one or more for that purpose, so > it does not require any multiplexing or whatever. How many of them do you > need? > I just need one. Is it a different irq than the RTC? It would be nice if we could avoid going through the s2idle_loop code. > Thanks, > > tglx >
