RADV Vulkan Driver Lands FreeSync/Adaptive-Sync For Mesa 19.1

While on the kernel-side there has been FreeSync support with the AMDGPU DRM driver since Linux 5.0 and for the OpenGL driver with RadeonSI there has been this functionality in Mesa 19.0 when paired with a supported kernel, the Mesa Radeon Vulkan driver has missed out on this action until now. But landing just in time for the Mesa 19.1 feature freeze is now the FreeSync/Adaptive-Sync enablement for RADV.

The FreeSync enablement patch for RADV is quite small with the AMDGPU kernel driver doing the heavy-lifting. The problem has been RADV lacking a config system for selectively enabling this variable rate refresh technology when running supported games or rather a blacklist for ensuring it doesn't get turned on for desktop compositors / web browsers / media players and other unsupported applications. Admittedly there aren't many Vulkan applications or other non-game programs, but with GTK4 sporting a Vulkan renderer and the possibility of Vulkan-powered compositors, it's a real problem.

Thankfully though RADV began working on DriConf integration to leverage the existing configuration management infrastructure used by RadeonSI and other Mesa OpenGL drivers.

That config system support for RADV was merged today and that cleared the way for enabling the adaptive_sync DriConf option and flipping it on by default after adding the few dozen lines of code needed for getting the feature in place.

Should you be living under a rock the past few years, FreeSync (or also VESA Adaptive-Sync) aims to reduce tearing and stuttering primarily for gaming with this adaptive synchronization technology. Since earlier this year NVIDIA's Linux driver has also been supporting this technology under the "G-SYNC Compatible" label to complement their higher-end G-SYNC displays.

The Mesa 19.1 feature freeze starts next week while the first release (19.1.0) is expected around the end of May.