VC4 Gallium3D Adds DMA-BUF Support, Yields Working DRI3

Beyond the VC4 Gallium3D work yesterday landing in Mesa that led to this Raspberry Pi graphics driver potentially running much faster, DMA-BUF support was also added.

Eric Anholt committed DMA-BUF support to the VC4 driver stack for zero-copy buffer sharing, with most other Linux graphics drivers already supporting DMA-BUF.

With the VC4 DMA-BUF support in place from the Gallium3D user-space driver side, the driver is far enough along that DRI3 is now working atop this driver configuration when using xf86-video-modesetting with GLAMOR acceleration. The VC4 driver stack is relying upon the generic mode-setting driver and isn't creating any custom DDX driver for the hardware. Eric so far has been hitting great results with this generic DDX that just depends upon the system having a proper DRM/KMS kernel driver.

These latest VC4 improvements will be found in the next major release of Mesa, Mesa 10.5 due out by the end of Q1'2015, which might be known as Mesa 11.0 should OpenGL 4.0 support be complete in core Mesa.