Assuming LINEAR modifier as default when driver doesn't expose any modifiers
Some additional read which "led" to this: https://patchwork.kernel.org/patch/10936631/
It seems "drivers that don't support the modifiers API as supporting the linear
modifier only, or in the DRM/KMS core by reporting the linear modifier for drivers that don't explicitly
support modifiers" do not hold up for nouveau. We don't have a
IN_FORMATS plane property and the fallback
to assume LINEAR results in blank screen.
Initial report comes from !218 (comment 387105), which reports some additional flickers/garbled output. The flickering seems to be an entire different issue.
I've only seen a blank screen with it.