Expanded AMD HDMI 2.1 support is coming to Linux

One area that's lacking on Linux right now is support for later versions of HDMI with AMD GPUs, but it seems expanded features are coming.

Some of this has been held up by the HDMI Forum, as they previously rejected an open source implementation of HDMI 2.1 with it being proprietary tech (and why we much prefer DisplayPort on PC).

Now though AMD developer Harry Wentland sent in a patch series to the Linux kernel developer list noting it brings "HDMI FRL support to the amdgpu display driver" and that "DSC is still being tested and will be sent out later". More from the full post:

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.

And, in a forum post on Phoronix an AMD driver developer actually said "A full implementation will ultimately be available once the patches are ready and have completed compliance testing" - so it appears the wait for better HDMI with AMD GPUs on Linux may be over during 2026.

It will be interesting to see how they managed to get around the HDMI Forum licensing requirements.