On Tue, Mar 05, 2013 at 02:34:25AM +0000, Tang, Feng wrote: > Hi Jason, > > Sorry, I forgot to add you in cc list in the first place. Please > help to review the patch series, thanks!
Sure, I didn't get CC'd on the patches, so this is an imperfect reply, but.. Did you consider an approach closer to the function I outlined to Jonh: // Drops some small precision along the way but is simple.. static inline u64 cyclecounter_cyc2ns_128(const struct cyclecounter *cc, cycle_t cycles) { u64 max = U64_MAX/cc->mult; u64 num = cycles/max; u64 result = num * ((max * cc->mult) >> cc->shift); return result + cyclecounter_cyc2ns(cc, cycles - num*cc->mult); } Rather than the while loop, which, I suspect, drops more precision that something like the above. (replace cyclecounter with clocksource) At the very least, keeping it as a distinct inline will let someone come by one day and implement a proper 128 bit multiply... You may want to also CC the maintainers of all the ARM subsystems that use read_persistent_clock and check with them to ensure this new interface will let them migrate their implementations as well. > * Solve the problem of judging S3/S4, as the clocksource > counter will be reset after coming out S4. Hrm, what if it wraps during suspend? This probably isn't a problem for a 64 bit TSC though.. Is it impossible to track if S4 or S3 was entered in the clocksource? Reagrds, Jason -- 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/