AMDGPU Driver Reverting The Buddy Allocator For Linux 5.19

The AMDGPU kernel graphics driver had been preparing to make use of the buddy allocator started by the Intel Linux graphics driver. But now with today's batch of DRM fixes that AMDGPU support is being reverted for Linux 5.19 due to it causing garbled screens for some users.

This buddy allocator is an implementation of the well known buddy system for dividing of memory into equal parts (buddies) and continuing equal splitting that until able to satisfy the memory request. Intel worked on the buddy allocator bits as part of their video memory changes as part of bringing up discrete GPUs with dedicated video memory.

The AMDGPU buddy allocator use was set to premiere in Linux 5.19 while as of today it's being backed out.

The AMDGPU buddy allocator support is being reverted this cycle due to "few users reported garbaged graphics as soon as X starts" and so is being reverted until the issue(s) are sorted out in a future Linux kernel cycle. This sounds like the issue I've been having with various Radeon graphics cards since Linux 5.19-rc1 on the Radeon RX 6800 XT and others, which is why I haven't carried out any Radeon Linux 5.19 vs. 5.18 benchmarks and the like. So hopefully this buddy allocator revert takes care of that and I can get on to more benchmarking.

Today's DRM fixes pull also has a DP MST blank screen fix for AMDGPU, a deep color fix in the DCE code, and other Radeon fixes. Plus there are several Intel i915 driver fixes too.

This pull doesn't have a fix for the Intel Alder Lake P GuC firmware breakage I wrote about yesterday. But DRM maintainer David Airlie issued a stern message to fix it and added in today's pull, "The outstanding firmware regressions reported by phoronix will hopefully be dealt with ASAP."