FreeSync / VESA Adaptive-Sync is not available on SteamOS

System information

AMD Radeon 290X
Steam client version: any
SteamOS version: any
Opted into Steam client beta?: No
Opted into SteamOS beta?: No
Have you checked for updates in Settings > System?: Yes

Description

Now I know, it's not purely Steam's area of responsibility. But variable refresh rates have a huge impact on the gaming experience. It allows tear-free gaming without the stutter or input lag introduced with V-Sync. Please see the whitepaper for details. This feature has been available on Windows for a few years and was more recently also introduced on XBox. The fact that several hundreds of Adaptive-Sync capable monitors are on the market proves that the technology has gotten very popular in a short amount of time. I think many people are waiting for FreeSync to happen on Linux/SteamOS and Valve recently announced that

our reasons for striving towards a competitive and open gaming platform haven't significantly changed. We're still working hard on making Linux operating systems a great place for gaming and applications.

Helping bringing VESA Adaptive-Sync (AMD FreeSync) to Linux would be a big step into this direction.

However, it's quite clear that it can't be a vendor or distinct steam implementation since SteamOS changed to the free and open graphics driver stack in version 2.115. There is an ongoing discussion (e.g. here) in the Linux community, involving developers from different hardware vendors, kernel maintainers etc. In that thread, valve devs have also been pinged, but they haven't responded to the mailing list:

I mean we have the guys from Valve on this mailing list so I think we should just get the feedback from them and see what they prefer.

However, those discussions have started a few times and, afaict, so far always ended up in silence. I know that Valve has made some great contributions to free software, helping the Linux graphics stack to evolve. So if there is any chance Valve will help find a consensus, help bringing Adaptive Sync to Linux, please have a look.

Another reason that might be of interest is that, while AS has been optional in DisplayPort versions 1.2a+, HDMI 2.1 introduces VRR as a mandatory feature. So if any vendor would like to sell a steam box with HDMI 2.1, it would have to support VRR.

Steps for reproducing this issue:

Install SteamOS
Recognise you don't have FreeSync capabilities

ValveSoftware / SteamOS