Andres Rodriguez sent in a message to the mesa-dev mailing list announcing 'gputool' for debugging AMD graphics cards on Linux. It's also open source under the GPL, so that's awesome.
Mesa has another patch that will be interesting for Linux gamers. This is actually a two-part fix as it was re-worked. The Witcher 2 should have a lot less black flickering with this latest patch.
If you had tried playing XCOM: Enemy Unknown (not to be confused with XCOM 2) on radeonsi and had it crash constantly, the good news is that this should now be fixed as of Mesa 13.0.3.
Divinity: Original Sin is one game that the open source Mesa drivers currently cannot run without hacks, but it looks like the Mesa team has been testing it.
I recently pointed out that Marek sent in patches to the Mesa list which could improve Deus Ex: Mankind Divided performance on RadeonSI around 70%, well all of the patches are now in Mesa git.
With Mesa coming along rather nicely in the latest releases, Feral Interactive are requesting that Canonical push out Mesa updates to their official graphics driver PPA to help Feral officially support Mesa in their Linux ports.
Not long after the big Mesa 13 release, we have a release candidate ready for a point release. It's an interesting one too, as it will include a performance improvement to the Intel Vulkan driver, as well as assorted bug fixes.
This release is a bit massive when it comes to actually looking at the features. Everything we have been hyped about recently is now in the stable release.
Marek, the well known contributor to Mesa has been working on some form of Mesa OpenGL threading, and his test showed a 70% improvement for Borderlands 2.
A recent commit to Mesa that improves performance in radeonsi was emailed in, as it mentions Batman: Arkham Origins in a list of tested games, where all of them are native on Linux apart from that one game. Updated: no it isn't.
As of today Mesa now has full OpenGL 4.4 support (with 4.5 already done) for both AMD radeonsi and Intel (i965/gen8+). Mesa won't actually expose any higher than OpenGL 4.3 until Mesa (well, someone) pays up for the Conformance Tests.