Provided by: linux-doc-2.6.15_2.6.15-23.39_all
device_suspend - Save state and stop all devices in system.
int device_suspend (pm_message_t state);
state Power state to put each device in.
Walk the dpm_active list, call ->suspend for each device, and move it
to dpm_off. Check the return value for each. If it returns 0, then we
move the the device to the dpm_off list. If it returns -EAGAIN, we move
it to the dpm_off_irq list. If we get a different error, try and back
If we hit a failure with any of the devices, call device_resume above
to bring the suspended devices back to life.