Nouveau Open-Source NVIDIA Driver Begins Tackling HDMI 2.0 Support
HDMI 2.0 allows for 18 Gbit/s bandwidth and can carry 4K video at 60Hz with 24 bit/px color depth. HDMI 2.0 also allows for up to 32 audio channels, new color spaces, new 3D formats, and various other capabilities.
HDMI 2.0 has been out for years while now the bits for the Nouveau DRM driver are in the works. At the moment the functionality like 12/16 bpc, YUV420, and other bits are not in place but just the basic implementation.
Mirkin posted the initial patches to the DRI-devel list while he's still working on more testing and possible improvements to this code.
Granted, running 4K@60Hz with Nouveau might not be too practical for now considering for Maxwell2/Pascal the open-source driver is limited to running at its boot clock speeds that are often very limited and thus the performance especially poor in areas outside of basic desktop compositing... Any 4K gaming on Nouveau is likely to be incredibly slow in all but the most basic games.