Created attachment 98783 [details]
test F: dmesg of glxgears without tiling (second patch by Michel Dänzer)

No change at all between the different no-tiling patches. With yours, Michel, I
also get only a black rectangle (no gears at all) and the same gpu reset cycles
as before with screen corruption. Tested this time with "Xorg -retro" as well
as only "Xorg".

By the way, my kernel command line includes:
    radeon.dpm=0 drm.rnodes=1
And in xorg.conf.d in the "Module" section:
    Load "dri2"
    Load "glamoregl"
And in the "Device" section:
    Driver "radeon"
    Option "NoAccel" "false"
    Option "AccelMethod" "glamor"
    Option "ColorTiling" "false"
    Option "ColorTiling2D" "false"