If you are a Linux gamer and use an AMD Radeon graphics card, you may know that there are all sorts of limitations and errors when trying to work at high resolutions and high refresh rates when using the HDMI port. AMD's software engineers had been working on a solution to all this by implementing parts of the HDMI 2.1 specification into the code, but unfortunately had to put the entire project on hold because the HDMI Forum rejected the project.
The disappointing news was reported by Phoronixwho discovered a brief explanation of the problem one of AMD's Linux engineers. If you're trying to run something like a 4K display at 120Hz on a Radeon RX 6000/7000 series graphics card via its HDMI ports, you'll run into problems when using Linux. You wouldn't expect that, as AMD clearly advertises HDMI 2.1 support on all of these models.
However, this only applies to Windows-based PCs as the authoritative body for the port's specifications (HDMI forum) does not allow use in open source software. AMD would be aware of this fact as it has been a member of the group for a long time. It's not clear what the exact problem is, but I strongly suspect it's related to the numerous technologies developed by other group members who don't want their work to be open source.
Either that, or it's the media companies on the forum who believe that anything involving open source will immediately result in DRMs being hacked and all their content being immediately pirated.
AMD tried to reach an agreement with the HDMI Forum and probably include only the bare minimum of the HDMI 2.1 specification to solve the high resolution issue, but ultimately the legal teams involved simply put an end to the whole thing.
All of this means that Linux gamers with Radeon GPUs will still need to use the DisplayPort output and a suitable DP to HDMI cable if they want to drive an HDMI-only 4K display at 120Hz or higher. However, finding a device that works isn't easy, and cheaper models will only cause more problems.
Or, to mix things up a bit, they could switch to an Intel Arc or Nvidia GeForce graphics card, since the Linux drivers for these fully support the HDMI 2.1 specifications. How did they do it but not AMD? In the former case Many Arc cards have an additional chip on the circuit board This does a DP to HDMI conversion and this probably applies to Nvidia's cards as well.
So if these GPUs can offer full HDMI 2.1 support, all is not lost with AMD's graphics cards.
