This year was the fourth year in a row that a bunch of display driver and compositor developers met for the Display Next Hackfest , to discuss, present, and tackle issues related to displays, GPUs, and compositors. Thanks to Collabora (Robert Mader and Mark Fillion specifically) for continuing this tradition!

(Check out the 2025 edition )

This time we met in Nice, France, after Embedded Recipes and right next to the PipeWire and libcamera hackfests. I took the opportunity to have a chat with the PipeWire developers about Flatpak, Portals, and the direction we would like to take in regard to video and audio access. Arun Raghavan has a nice summary if you’re interested.

That also brings me to another point: I have mostly stopped working on compositor and color-related areas. It’s not because I lost interest, but rather that I took over Flatpak and Portals maintenance. That by itself was taking a big chunk of time, but then LLMs became good at finding security vulnerabilities and now this takes more time than I have.

Before the hackfest, I sat down for one week and hacked on Mutter (the GNOME Shell compositor) to create a prototype with all the changes I wanted to do but never found the time for:

• dropping colord
• configuring ICC profiles and white point via the display config
• splitting our color transformation code to provide a color pipeline
• offloading color transforms to the KMS color pipeline
• achieving color-accurate white point adjustment and night light

With the prototype done, I made my way to Nice, taking a sleeper train from Paris and waking up to the Côte d’Azur in the morning. Then I met with Robert in the botanic garden, where he used his deep cross-stack offloading knowledge to test a bunch of video playback scenarios.

Over the hackfest days we found some glitches in the AMD driver, which were promptly fixed by Harry Wentland. We also had some discussions on strategies to do KMS color pipeline offloading, which prompted some changes in the prototype, and now have something we can start upstreaming.

For the KMS color pipeline, we got a new fixed matrix operation for YCbCr to RGB conversion, and new named curves for important video playback cases. We talked about control over the color format on the cable (which has been merged by now), as well as control over the minimum BPC.

Another thing that we all got annoyed by was all the funky colors our in-kernel console became when our offloading worked a bit too well. We’ve wanted a reset mechanism for KMS for a few years now anyway, so we decided to prototype it and test it on Smithay. Proper patches are now on the mailing list thanks to Maxime Ripard.

Mario Limonciello managed to push out patches for backlight support via KMS before the hackfest – another thing we’ve wanted for years. We tested them on Mutter, and KWin added support for it as well.

Xaver Hugl showed that we can easily support AMD FreeSync Premium Pro, the worst name for a feature that is essentially Source-Based Tone Mapping (SBTM). We also got good news regarding SBTM on HDMI. In general, it looks like we might finally get HDR that isn’t entirely awful.

DisplayID, the replacement for EDID, is going to become much more prevalent, and we discussed how we’re going to roll out support in the kernel and in libdisplay-info.

We once again managed to put enough wayland developers in a room for a bigger protocol change to get merged. This time it was multi device dmabuf feedback which made Victoria Brekenfeld happy.

There was a lot more happening — check out Xaver’s and Louis Chauvet’s blog posts.

Even though I wasn’t as prepared as the previous times, it was very productive and there was more actual hacking this year. I also enjoyed meeting everyone again a lot, hanging out in the water while watching the 1% take off in their private jets, struggling to find an adequate Döner, and eating lots of pizza.

Until next time!