Hi Thomas, On 23 January 2015 at 05:07, Thomas Gleixner <t...@linutronix.de> wrote: > On Thu, 22 Jan 2015, Xunlei Pang wrote: >> When doing timekeeping_resume(), if the nonstop clocksource >> wraps back, "cycle_delta" will miss the wrap time. >> >> It's hard to determine the right CLOCKSOURCE_MASK(xxx) or >> something to add code for inspecting such behavior, and we >> don't have many existent nonstop clocksources, so just add >> a comment to indicate that if have this flag set, people >> are aware that this nonstop clocksource won't wrap back >> during system suspend/resume. > > -ENOPARSE > > What has the CLOCKSOURCE_MASK() to do with this and why is the fact > relevant, that we only have a few suspend_nonstop clock sources?
Before this, I tried to add some code to catch such problem at the time of registering the clocksource, like using the CLOCKSOURCE_MASK(), for example 64bit counter will never wrap for us. But there may be other values like CLOCKSOURCE_MASK(56), I just can't figure out exactly how to do this judge. So, I think we can only add a comment to let the developer be aware of this when registering nonstop clocksource, that's what I want to express. > >> + >> +/* >> + * When setting this flag, you're also supposed to mean that it doesn't >> + * wrap back during system suspend/resume. See timekeeping_resume(). > > -ENOPARSE > > I guess what you want to say here is: > > /* > * clocksource continues to run during suspend and is guaranteed not to > * wrap around during long suspend periods. > */ > Yes, this description is way better :-) Thanks, Xunlei -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/