Switching fb backend back to default

Hi

I'm working on making i915kms unload properly. I've come to what I think
is the last issue. The drm driver unloads ok, the "efifb" backend is
restored (according to logs) and vt_efifb_init() is being called but the
screen (laptop built in display) stays black. The system seems
operational otherwise. If I load i915kms again in this state I get back
a visible (i915kms) framebuffer.

Did we ever have this working so it's known to work?

Cheers

/Johannes