Clock offsets during suspend/resume

Andy Green andy at openmoko.com
Fri Dec 12 16:02:21 CET 2008


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Somebody in the thread at some point said:
| Hi!
|
| On 2.6.24, after each suspend/resume cycle, the system clock lags 2-3
| seconds more behind the hw clock and ntp. The amount of lag seems to be
| independant of the time spent in suspend.
|
| On 2.6.28 from andy-tracking i get an offset of 10 seconds per cycle.
| This kernel also takes a lot longer to resume because it has to scroll
| more kernel output (2 warnings about already enabled regulators, ...).
| The total time spent on the console during suspend and resume is also
| about 10 seconds.
|
| If we can't fix the system clock, could we restore it from the hw clock
| during resume?

Userspace should also be able to do it with

hwclock --hctosys

afterwards.

I guess what is going on is the rtc driver is restoring the clock, but
there is no "time" passing until resume completes.  If it is true, then
hwclock can be a reasonable solution.

- -Andy
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