- Edited
While browsing the intel-gfx archives I found this post > https://lists.freedesktop.org/archives/dri-devel/2017-September/152651.html
i915.enable_dithering allows to force dithering on all outputs on (=1) or off (=0). The default is -1 for current automatic per-pipe selection.
This is useful for debugging and for special case scenarios,e.g., providing simulated 10 bpc output on 8 bpc digital sinks if a 10 bpc framebuffer + rendering is in use.
A more flexible solution would be connector properties, like other drivers (radeon, amdgpu, nouveau) already provide. A global override via module parameter is useful even with such connector properties, e.g., for scientific applications which require strict control over dithering, to have an override for DE's which may not expose such properties via some standard protocol in a user-controllable way, e.g., afaik all currently existing Wayland compositors.
This is from 2017 so I don't know if this was eventually implemented, or if the author is an Intel dev (I assume so).