(In reply to Shawn Anastasio from comment #2)
> Upon further testing, the issue seems to go away when the firmware is
> removed from petitboot, preventing it from initializing the card before the
> host OS. This indicates that it may have something to do with the GPU being
> initialized twice.

The hw requires a special reset before it can be initialized again.  This is
handled in driver for things like hibernate (S4) support.