After performing just an FLR (PCI function level reset) of a Gen8 Intel HD graphics device, there's no VGA output from the device, no matter what I try to do.  I've had coreboot reset the graphics control register, VGA control, VGA display disable bit, etc. 

Has anyone seen anything like this?  The only way I can get VGA restored is by performing a system-level reset.  But I just want to do an FLR.  Any ideas?