This wasn't an open source driver, this was a hardware abstraction layer that they wanted in the kernel so their Windows driver could be distributed under a pro

This wasn't an open source driver, this was a hardware abstraction layer that they wanted in the kernel so their Windows driver could be distributed under a proprietary license and used without a kernel recompile. A year ago AMD said they would just use what is currently in the kernel with a few minor modifications to get their driver working in userspace, apparently they did not follow through on that though