Dual head RADEONHD – screen blanking

I recently upgraded xorg on my workstation at the office. Immediately I started seeing problems with one of the monitors. It would go empty/blank/black for three seconds, then resume normal operation. Then it would go blank again when I interacted with the screen. In short, that one monitor was completely useless.

Swapping cables on the dual head video card moved the problem to the other monitor.

All software was the latest version:

  • xorg 7.5
  • FreeBSD 8.1-STABLE Wed Aug 11 14:34:19 EDT 2010

Eventually I stumbled upon the solution which was initially recommended to me, but which I was unable to correctly implement at the time. It was user error. Initially, I tried:

Option     "NoAccel"   true

Today I tried:

* Option     "NoAccel"   "True"

After starting X again, /var/log/Xorg.0.log contained:

(II) RADEONHD(0): Disabling HW 2D acceleration.

This has now made the system useable. SImple fix. But it’s a shame we can’t use the hardware acceleration.

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