https://bugs.freedesktop.org/show_bug.cgi?id=53130
--- Comment #4 from Andreas Boll andreas.boll.dev@gmail.com --- (In reply to comment #3)
I've rebuilt mesa with this re-enabled and I saw a lot of rendering glitches. I suspect that DISCARD_RANGE being re-enabled is the problem, although I've also built and installed an updated xf86-video-ati (cdf522f→20bfc65).
My current mesa build has 1eedebc reverted; I'll re-check with that undone later.
Do you still have the rendering glitches with enabled DISCARD_RANGE? If so please reopen this bug.