At the beginning of the month was the surprise milestone of AMD posting AMDGPU kernel driver patches for HDMI 2.1 Fixed Rate Link (FRL) support. The HDMI FRL patches have since been updated to also enable HDMI 2.1's Display Stream Compression (DSC) functionality for higher resolutions and higher refresh rates with the open-source AMDGPU driver.

Display Stream Compression with HDMI 2.1+ allows for higher refresh rates and resolutions like 4K@240Hz and 8K@120Hz with this visually lossless, low-latency compression for better bandwidth efficiency. AMD tacked on HDMI FRL DSC support to the HDMI FRL patch series they've been working through to get into the mainline Linux kernel.

As noted as an update in the earlier Phoronix article, it's been confirmed via our forums that ultimately AMD is working on a full HDMI 2.1 implementation for the AMDGPU open-source Linux driver. As for what changed to ultimately allow AMD to publish the open-source code for their HDMI 2.1 driver support still isn't clear as previously it was blocked by the HDMI Forum. There is some speculation that it may be due to Valve's involvement that a workaround or compromise was achieved.

Sent out today was the latest patches for HDMI FRL and FRL DSC for the AMDGPU driver. The patch cover letter notes that the patch series should land with the next AMDGPU Display Core (DC) patch series. With that said, it's quite likely then we will see this support upstreamed to the mainline Linux kernel with the upcoming Linux 7.2 cycle.