Following the recent release of FSR 4 support on RDNA 3 GPUs, Valve engineer, Pierre-Loup Griffais, has announced in a post on Bluesky that the same support has officially been added to Linux via Steam's Proton compatibility layer. Support for FSR 4 on RDNA 3 comes by way of the latest version of Proton Experimental, so it's by no means a stable implementation just yet, but the engineer specifically calls out SteamOS and the Steam Machine as the target system for the new upscaler support, suggesting that Valve will invest development resources into getting the support into a more complete state ahead of the full roll-out of the Steam Machine.

Curiously, the post also specifically calls out devices with RDNA 3 discrete GPUs and the Steam Machine, suggesting that support for Radeon iGPUs, like the 780M and 890M that largely dominate the gaming handheld space has not yet been implemented. It's possible that Valve developers, who often contribute to Linux graphics drivers and gaming optimizations, may implement support for the gaming handhelds. There are also reports that manually adding support for FSR 4 on RDNA 3-based iGPU systems—via tools like OptiScaler, for example—results in a working implementation of the upscaler.