Power Managment (mpc83xx)

I have mpc83xx, and I work with Linux 2.6

I am trying to use power management states. 

I succeed to get into D1 state (echo standby > /sys/power/state),

And to waked up by GPIO.

But when I try tried echo mem > /sys/power/state it waked up by reset
(that stuck in the middle)

Or echo disk > /sys/power/state didn't went to sleep at all.

There is a way to get into economic power state (less power then D1
(standby)) and to wake up fast?