https://bugs.freedesktop.org/show_bug.cgi?id=74347
--- Comment #8 from Marek Olšák maraeo@gmail.com --- (In reply to comment #3)
Please don't change the bug component. DRI/Radeon is R100. You have R600 and your driver is part of Gallium.
The variable was just to help debugging. Please try also this:
R600_DEBUG=nocpdma
It looks like we should disable CP DMA on R6xx again.