On Tue, 24 Nov 2020 02:31:47 +0000
jbranso@dismail.de wrote:

> All AMD graphics cards are virtually useless on the Linux
> libre kernel.
Not all of them.

The issue is that I've been the only one working on making ATI/AMD GPUs
somewhat useful on linux-libre by making the radeon driver work:
- In contrast with the VESA driver and UEFI equivalent (efifb?),
  having the radeon driver working enables the right resolution, multi
  display, and probably some other features too that makes such GPUs
  much more usable.
- As I only worked around the lack of firmware, 3D still doesn't work.
  To work it would probably need someone to work on free firmwares.
- Like with nouveau, it depends on bytecode that is AFAIK nonfree and
  that probably contains code. That bytecode is in the video BIOS.
- I'm unsure of the status of video BIOS replacements for AMD/ATI GPUs,
  but AFAIK, like with Nvidia GPUs it's still an issue. Since it's
  useful to have a working display at boot (like in GRUB), it's a good
  idea to fix that too. I worked on doing that for Intel GPUs in
  Coreboot, along with other people that helped me, so it's possible.
  In addition GRUB (and probably radeonhd too) have some interesting
  code for some specific Radeons to init it without the bytecode and
  without the video bios AFAIK.

Since I don't have infinite time nor all the GPU families, and that
linux-libre requires patches to be tested before merging them, I didn't
add the GPU I don't have. I also don't have much time anymore for doing
that kind of work.

There is more information about this issue on the linux-libre wiki[1],
including a howto on how to add support for your GPU in linux-libre.

The amdgpu driver requires a bit more work, I started working on it by
helping someone on the linux-libre mailing list but it took me too much
time so I had to stop working on it.

References:
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[1]https://libreplanet.org/wiki?title=Group:Hardware/research/gpu/radeon

Denis.