Users of nVidia's proprietary driver are running into issues with the
introduction of 'simpledrm'. 

 
https://forums.developer.nvidia.com/t/510-39-01-on-5-16-0-kernel-green-screen/200476/7

There are workarounds available like

  a) patching the nvidia kernel module and no longer calling
pci_request_regions(...) function
  b) Kernel option  'initcall_blacklist=simpledrm_platform_driver_init' 
  c) Kerneloption ' fbcon=map:1'.

But the culprit is that nVidia doesn't remove the generic driver (e.g.
efifb/vesafb) first. This should be changed to address the real issue here.

API under MIT license

  https://elixir.bootlin.com/linux/latest/source/include/drm/drm_aperture.h

Example for nouveau driver.

 
https://elixir.bootlin.com/linux/latest/source/drivers/gpu/drm/nouveau/nouveau_drm.c#L765

Thomas is the author of 'simpledrm'. Please correct me, if I misunderstood
anything and feel free to add more details here.