Correction.
These two combinations gave the VCE fail resume error on bootup.
radeon.si_support=1 radeon.cik_support=0
radeon.si_support=1 radeon.cik_support=1
These two did not.
radeon.si_support=0 radeon.cik_support=0
radeon.si_support=0 radeon.cik_support=1
Sorry for the confusion.