Radeon X.Org Driver Now Only Uses DRI3 By Default With GLAMOR
Just as a heads up for those with pre-GCN AMD GPUs where there is EXA support, Direct Rendering Infrastructure 3 is no longer being enabled by default with this older means of hardware-specific 2D acceleration. AMD's Michel Dänzer made the change to no longer enable DRI3 by default with EXA, he explained, "it doesn't work correctly in all cases. I'm not sure this is fixable, given EXA's architecture."
Michel referenced a bug report where DRI3 screen corruption is happening when using Radeon EXA but DRI2 rendering works fine.
Today's Git commit is just a change about the default behavior, you can still manually enable DRI3 with EXA, or if you're still on EXA you may be better off trying to enable GLAMOR to see if it improves your 2D Linux experience.