# cat /sys/class/scsi_host/host0/link_power_management_policy
In my case i think it is "disabled", since it is in max_performance...
Echoing it a "min_performance" would enable it. That change is not permanent.
Do you want to disable it for any particular reason?
There is also pcie_aspm (active state power management) that (at least for me) caused
a lot of problems witch certain hardware.