RADV Mesa Driver Lands Several NGG Stream-Out Fixes

Open-source graphics driver engineer Samuel Pitoiset of Valve's Linux team landed a number of stream-out fixes this week for RADV's Next-Gen Geometry (NGG) Stream-Out handling.

When testing on RDNA2 with NGG stream-out enabled, Samuel Pitoiset is now able to enjoy a 100% pass rate for OpenGL transform feedback test cases when making use of the Zink OpenGL-on-Vulkan implementation atop RADV.

Besides these fixes being useful in their own right and with current GPUs when running with NGG stream-out enabled (the RADV_PERFTEST=ngg_streamout environment variable), this is also important moving forward to RDNA3 / Radeon RX 7000 series GPUs where NGG is now always enabled with the future AMD GPUs. In part this is why over the past several months the open-source AMD graphics driver code has been seeing a lot of NGG fixes -- both for RadeonSI Gallium3D and RADV Vulkan.

It's always great seeing all of the improvements being made to the open-source Radeon Linux graphics stack by Valve not only for the Steam Deck but benefiting all newer Radeon GPUs too.