AMD Developers Begin Making Open-Source FreeSync/AdaptiveSync Plans

While the AMDGPU DC code is expected to land for Linux 4.15 with goodies like Vega display support, HDMI/DP audio, and atomic mode-setting, one of the sought after display features won't be initially supported: FreeSync or the VESA-backed AdaptiveSync.

As we've known for a while, while AMDGPU DC fills out the requirements for being able to support FreeSync, the last bits of the implementation are not present as the interfaces are basically yet to be decided among the open-source driver developers. While AMD can post their existing FreeSync code as found in AMDGPU-PRO hybrid driver, they are trying to come up with a more standardized interface that will satisfy the other upstream Linux driver developers too that might want to support AdaptiveSync.

FreeSync/AdaptiveSync as a reminder is a means of adaptive synchronization for monitors to support a dynamic refresh rate with a goal of reducing screen tearing, particularly for gaming. Adaptive-Sync is present since DisplayPort 1.2a. Besides trying to reduce screen tearing and stuttering, this tech can also reduce power use (or extend battery life) by reducing the refresh rate when the screen is static.

Nicolai Hähnle of AMD today posted a basic Mesa patch for reference showing how via this new driconf option it could request FreeSync be enabled via the AMDGPU-PRO hybrid driver's AMDGPU DDX / X11 protocol extension. That patch isn't intended to be upstreamed as-is but for getting the ball rolling to discuss with other driver developers.

Nicolai then started a Mesa mailing list discussion for talking about upstream FreeSync/Adaptive-Sync support and for trying to align the KMS/X11/Wayland interfaces around this effort.

We'll see what comes of this in the days and weeks ahead, but long story short is you will need to be waiting a bit longer to enjoy FreeSync/Adaptive-Sync on a fully open driver stack.