Power Island states can be read back from PMU global registers. Here is the command to read out the power state register:
targets -set -filter {name =~ "PSU"}
# Read Power Status of Islands
rrd pmu_global pwr_state
# Example Output:
pwr_state: 00dffcbf
pl (Bits [23]): 1 fp (Bits [22]): 1 usb1 (Bits [21]): 0
usb0 (Bits [20]): 1 ocm_bank3 (Bits [19]): 1 ocm_bank2 (Bits [18]): 1
ocm_bank1 (Bits [17]): 1 ocm_bank0 (Bits [16]): 1 tcm1b (Bits [15]): 1
tcm1a (Bits [14]): 1 tcm0b (Bits [13]): 1 tcm0a (Bits [12]): 1
r5_1 (Bits [11]): 1 r5_0 (Bits [10]): 1 l2_bank0 (Bits [7]): 1
pp1 (Bits [5]): 1 pp0 (Bits [4]): 1 acpu3 (Bits [3]): 1
acpu2 (Bits [2]): 1 acpu1 (Bits [1]): 1 acpu0 (Bits [0]): 1