Hi Patrick
No worries ! the chasis and server will run, even after FI is on 2.2
see eg.
http://www.cisco.com/c/en/us/td/docs/unified_computing/ucs/sw/upgrading/from2-0/to2-2/b_UpgradingCiscoUCSFrom2-0To2-2.html
Typically, you would upgrade first UCSM to 2.2, the do "autoinstall infrastructure", and then finally either do manual or also "autoinstall server", blade by blade.
I assume of course, that you have a maintenance policy with explicit ACK in place.