Thank for the detailed answer and showing a way forward. I don't think however I'll have the time and skill to make any real progress.
Indeed my main interest is the freedom aspect. Coreboot has given me greater control over my technology and I am on the lookout to get better technology without giving up (much) of that freedom.
Can you elaborate on the PSP in recent AMD GPUs? I searched the internet and read AMD documentation but couldn't find anything on it. Some specific references would be great. Also, what would be the scope of such a PSP? If it can have direct memory access there could be security risks of the PSP doing malicious things, but with IOMMU the practical risk will be quite low. (I lack knowledge on this topic). So then the main issue with the PSP is that it prevents custom firmware through signatures.
I'm looking to drive larger display resolutions compared to the i7 3770 and have OpenCL compute power for Darktable editing. In the meantime I found out that the RX590 requires the AMD Pro(prietary) drivers for OpenCL support like most AMD GPUs do. OpenCL is pretty broken for AMD GPUs, which is well summarized in this post by Thomas Debesse https://rebatir.fr/post/2022-01-25-OpenCL_on_Linux_state_of_AMD_drivers_is_n...
It seems the GPU situation as a whole will soon improve with so many efforts underway: - Rusticl for better and universal OpenCL support in Mesa - Nvidia also going the open source driver route - continued development for ARM GPU support - Apple M1/M2 GPU support getting there, which might provide transferable knowledge - LibreSoC developing a SoC including GPU from the bottom up
I cleary can't have it all at the moment so I think I'll wait to see what comes of the efforts mentioned above. Most likely Rusticl will be released and will enable OpenCL without having to use proprietary drivers. But free firmware on GPUs doesn't seem realistic given the low interest from the community.
Best, Nico