This new header defines four ACPI control methods used by AMD graphics hardware and then related functionality to them. The four AMD ACPI methods are ATIF, ATPX, ATRM, and ATCS.
The new header can be viewed on the dri-devel mailing list. The header file is over 400 lines of new code.
While the patch integrates the new AMD ACPI header file and updates the relevant code, still on the TODO list is hooking up and handling ACPI notifications, making PowerXpress code more robust, and implementing PCI Express Gen and width switching using ACPI.
This new AMD ACPI header file came shortly after John Bridgman was mentioning in our forums that they are working to release new power management code for their open-source Radeon Linux graphics driver. "...AMD has not yet opened up all of the PM bits of the GPU (but as I said before we are working on that again since it doesn't look like community devs are going to go any further with what has already been released), so it loses in the performance-per-watt when the system is idle (an oxymoron if ever there was one)..."