It's not complete HDMI 2.1 support but to much surprise hitting the mailing list today were official patches from AMD for implementing HDMI Fixed Rate Link "FRL" support for their kernel graphics driver. HDMI FRL as part of HDMI 2.1+ allows for higher bandwidth to support higher refresh rates and resolutions.

The HDMI Forum has long [1]held up AMD from implementing HDMI 2.1 in their open-source Linux driver for not divulging HDMI IP that the forum doesn't want to make public. This lack of HDMI 2.1+ support in the AMDGPU driver has been a major pain point for Radeon Linux users and has led to [2]experimental patch alternatives developed by the open-source community outside of AMD.

As a surprise today are AMDGPU driver patches for HDMI FRL support albeit to be very clear is just FRL and not the full HDMI 2.1 support with variable refresh rate (VRR) or other features. Longtime AMD Linux engineer Harry Wentland explained in today's patch cover letter:

"This patch series adds HDMI FRL support to the amdgpu display driver. DSC is still being tested and will be sent out later.

This work passed a representative subset of HDMI compliance and a full compliance run on this branch is in the works. We don't expect the full run to show any failures since it passes in other environments.

Thanks to Siqueira who prepared this work a couple years back and unfortunately didn't manage to send them while he was still working at AMD.

Thanks to Jerry who has been making this code solid on Linux and running the compliance tests.

The first patch in the series isn't related to HDMI 2.1 but included here because it moved the code around some key bits of the HDMI 2.1 stuff around too much. It will land with the next DC Patch series."

Exciting to see and curious to what has changed for finally allowing AMD to publish these HDMI 2.1 FRL patches.

The work is out for review on the [3]Linux kernel mailing list . Hopefully it will be ready for merging by the time of the Linux v7.2 merge window this summer.

UPDATE: Even more exciting... Per [4]this comment from a prominent AMD Linux developer, it looks like a full HDMI 2.1 implementation for AMDGPU could be coming!



[1] https://www.phoronix.com/news/HDMI-2.1-OSS-Rejected

[2] https://www.phoronix.com/news/AMDGPU-HDMI-2.1-FRL

[3] https://lore.kernel.org/amd-gfx/20260501140441.41068-1-harry.wentland@amd.com/

[4] https://www.phoronix.com/forums/forum/phoronix/latest-phoronix-articles/1631149-amd-posts-hdmi-2-1-frl-patches-for-their-amdgpu-linux-driver?p=1631154#post1631154