[radeon] plasma screen corruption/nothing to click on except crash notifier -> black screen

[Kevin Kofler]

Felix Miata wrote:
> host fi965
> 01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI]
> RV370 [Radeon X600/X600 SE] using radeon driver
> F23 x86_64 freshly dnf upgraded from last same about 10 weeks ago (4.2.rc8
> kernel)
> initial screen corruption eventually clears to black
> plasmashell PID 1621/1667/1687 segmentation fault (11)
> multi-user.target startup -> startx
> IIRC, theme selected is whatever alternative to Breeze was found, likely
> Oxygen If I un-disable compositing (set via xorg.conf*), crash notifier
> never appears, and screen corruption remains until Ctrl-Alt-BS
> .xsession-errors is not being written
> no BRC bug on point less than 5 months touched last found

That looks like broken OpenGL support in the driver.

Trying the QT_XCB_USE_SOFTWARE_OPENGL workaround that was implemented for 
the drivers (like rv200) that don't do OpenGL 2 at all can't hurt. Of course 
it will be slower, but at least it shouldn't crash…

(You can try editing /etc/X11/xinit/xinitrc.d/10-qt5-check-opengl2.sh to 
leave only these lines:
  QT_XCB_FORCE_SOFTWARE_OPENGL=1
  export QT_XCB_FORCE_SOFTWARE_OPENGL
to set the variable unconditionally.)

        Kevin Kofler