LEAF with FEX upgrade with ACI

[is2019]

We are upgrading from Cisco APIC version 5.1(4c) to version 5.3(2c). What is the behavior of the FEX when upgrading the LEAF? Do the FEX ports shut down when the LEAF is rebooted? What does the FEX update when the LEAF is updated?
There is documentation of this FEX process with LEAF within ACI

[mabushei]

Ans- Once the parent leaf switch comes back online with the new software version, it will automatically push the new firmware to the connected FEX units.