I have a Samsung SyncMaster SA100. This monitor doesn't come with buttons to change the brightness, only a power button. The guys at Samsung say that you should change the brightness using a proprietary program that they made, like, 8 years ago and only works in Windows.
For the last couple years I've been changing the brightness of my monitor using DDCcontrol. It's a pretty old program, but it's the only one (that I know) that can change the brightness using DDC/CI.
The problem is that it worked fine with ATI's open source drivers, but with the closed source ones I get the following message:
Detected monitors :
No monitor supporting DDC/CI available.
If your graphics card need it, please check all the required kernel modules are loaded (i2c-dev, and your framebuffer driver).I already ran modprobe i2c-dev and modprobe radeonfb (which I believe is the frame buffer module needed.)
Is there a step I'm missing or another way to change brightness? Going back to the Open Source drivers is not an option as the screen tears a lot with them.
I am on Kubuntu 15.04 using XFCE and the GPU is an ATI HD 5670.
2 Answers
This is kinda old, but I had a similar problem, i was getting the same error message. I solved it by running the program with sudo.
sudo gddccontrolAs additional note regarding the ATI/AMD driver, since 16.04 Ubuntu forces the open source driver so if the proprietary driver was the problem, it can not be any more.
The fglrx driver does not create /dev/i2c devices, which is why the usual tools do not work with it. Instead, support for DDC communication is part of its API.
ddccontrol does have iftested code that appears to handle this case, so you may have luck building your own copy. I have not tested it.
You can also use the more recent ddcutil which uses the fglrx API for DDC communication. However, since the license in the fglrx header files prevents their distribution with ddcutil, you'll have to build your own copy. Instructions are here
