This should be, what you want, tried "sync; echo 1 > /sys/power/pm_trace; pm-suspend", but I do not think, that dmesg prints anything except "[ 2.507938] Magic number: 1:754:597".
This should be, what you want, tried "sync; echo 1 > /sys/power/ pm_trace; pm-suspend", but I do not think, that dmesg prints anything except "[ 2.507938] Magic number: 1:754:597".