I have some Amaranth DVI-D and TMDS goodies here:
- Timing gen: https://github.com/apfaudio/tiliqua/blob/main/gateware/src/tiliqua/dvi.py
- TMDS: https://github.com/apfaudio/tiliqua/blob/main/gateware/src/tiliqua/tmds.py
- Wishbone-backed framebuffer: https://github.com/apfaudio/tiliqua/blob/main/gateware/src/tiliqua/dma_framebuffer.py

It's been battle tested on about 10 different screens and an agilent N5998A. I also have a branch that adds CSRs for DVFS (runtime dynamic resolution switching). Would be interested in upstreaming it at some point if there's interest.