Double checked and confirmed for both 5.12.12 and 5.13.rc7: nomodeset: boots ok, no brightness amdgpu.backlight=0: does not boot, hangs at "fb0: switching to amdgpudrmfb from EFI VGA" nomodeset amdgpu.backlight=0: boots ok, no brightness I'll report this at gitlab.freedesktop.org as per your suggestion. I'll report back the reference when done. Thanks so much for your patience.