Raspberry Pi VC4 Driver Working To Reduce Overhead, Android Native Fence Support

Broadcom developer Eric Anholt has shared another weekly update concerning his summer 2017 hacking on the VC4 open-source driver stack that is most notably used by the Raspberry Pi.

Since the last update, he's been working on getting his VC4 XML branch ready for merging, which is an Intel driver inspired way for writing an XML description of hardware packets and using that to generate the relevant code for the driver. This is a cleaner way than his old code and allows for some new possibilities moving forward. He's got it where the performance difference is now similar with/without his XML-generated packing code. In other driver overhead work, he was able to cut the CPU overhead of draw calls by 5% as a result of a new Gallium flag.

Other recent VC4 work includes working on the 7-inch LCD panel support, ANDROID_native_fence support is about ready to land, and he's working on more NIR code. He's also now exposing detailed graphics memory usage information for the VC4 DRM driver via /debug/dri/0/bo_stats.

Last but certainly not least, he's also been working on some VC4 mode-setting code clean-ups. More details via this GitHub post.