root@vertex:/tmp$ bin/ddccontrol 'dev:/dev/i2c-3'
ddccontrol version 0.4.2
Copyright 2004-2005 Oleg I. Vdovikin (oleg@cs.msu.su)
Copyright 2004-2006 Nicolas Boichat (nicolas@boichat.ch)
This program comes with ABSOLUTELY NO WARRANTY.
You may redistribute copies of this program under the terms of the GNU General Public License.

Reading EDID and initializing DDC/CI at bus dev:/dev/i2c-3...
pcilib: Cannot open /proc/bus/pci
pcilib: Cannot find any working access method.
Corrupted EDID at 0x50.

DDC/CI at dev:/dev/i2c-3 is unusable (-2).
If your graphics card need it, please check all the required kernel modules are loaded (i2c-dev, and your framebuffer driver).