HDR and Colour Management patches for Steam Deck + AMD GPUs under review

Developer Melissa Wen recently sent in patches to improve HDR and Colour Management on Linux for Steam Deck and potentially other AMD GPUs. The work is being done by Melissa Wen, Joshua Ashton and collaboration with Harry Wentland.

Exciting stuff, as eventually with this we should see some HDR fun on Linux with the likes of Gamescope. In the RFC (Request For Comments) patches, it was also specifically mentioned that SteamOS 3.5 is aiming to have "gamut mapping, HDR, SDR on HDR, HDR on SDR, and much more".

Excerpts from the RFC:

Joshua Ashton and I (with the great collaboration of Harry Wentland - thanks) have been working on KMS color pipeline enhancement for Steam Deck/SteamOS by exposing the large set of color caps available in AMD display HW.
[…]
So far, we keep these properties' usage under an AMD display config option (STEAM_DECK). However, we are fine with having them fully available to other DCN HW generations. In the current proposal, we are already checking ASICs before exposing a color feature. We can work on 3D LUT resource acquisition details to fit them to DCN 3+ families that support them. Indeed, before moving to these config boundaries, we started working on an open solution for any AMD HW.

The userspace case here is Gamescope which is the compositor for SteamOS. It's already using all of this functionality (although with a VALVE1_ prefix instead of AMD) to implement its color management pipeline right now.

Sounds like developers on KDE are interested in the work too, with Wen noting that Xaver Hugl from KDE was interested in experimenting with it for their HDR / colour bring-up too.