On 01/24/2013 04:30 PM, Jon Hunter wrote: > Hi Vaibhav, > > On 12/31/2012 07:07 AM, Vaibhav Bedia wrote: >> AM33XX has two timers (DTIMER0/1) in the WKUP domain. >> On GP devices the source of DMTIMER0 is fixed to an >> inaccurate internal 32k RC oscillator and this makes >> the DMTIMER0 practically either as a clocksource or >> as clockevent. >> >> Currently the timer instance in WKUP domain is used >> as the clockevent and the timer in non-WKUP domain >> as the clocksource. DMTIMER1 in WKUP domain can keep >> running in suspend from a 32K clock fed from external >> OSC and can serve as the persistent clock for the kernel. >> To enable this, interchange the timers used as clocksource >> and clockevent for AM33XX. > > I have been thinking about this some more. In the case where we are > using gptimers for both clock-events and clock-source (on both AM33xx > and OMAP) and I am wondering if it makes sense to switch the timers so > that we use the always-on timer for clock-source and a different one > from clock-events. > > For OMAP, if we are not using the 32k-sync for clock-source, then we are > never going to achieve low power states during idle as we will always > have one gptimer running. And in this case, to your point below, it > would be better to use the always-on for clock-source so that in suspend > we can at least hit low power states and maintain time. I have posted a patch today [1] that I hope will address this issue for you. Can you give that a try? Cheers Jon [1] http://www.spinics.net/lists/arm-kernel/msg221265.html -- 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
