It is a kernel bug, limited to monitors connected via Display Port output to an Intel Integrated Graphics.
I found it googling [drm:intel_dp_i2c_aux_ch] *ERROR* too many retries,giving up
However, this bug has been fixed in Linux 3.16, which can be installed in Ubuntu 14.04. If you are running 14.10, you already have this kernel and you should not have to do this. You also have 3.16 if you have installed Ubuntu 14.04 from a 14.04.2 installation disk. It does not matter whether or not you are using Ubuntu 14.04.2 or not (which you are if you have been staying up-to-date), but if you used a 14.04.2 DVD or flash drive to do the installation. If you installed Ubuntu 14.04 with a 14.04 or 14.04.1 installation disk, there is a solution, which is explained below.
Linux 3.16 is available as an HWE kernel, a kernel that is designed for Ubuntu LTS users to get better hardware support, but it also fixes some bugs. However, I will warn you, that if you have been using Ubuntu for a while and have lots of different programs installed on your system, then you are at a small risk of experiencing minor bugs, such as an application having slightly unusual behavior. It is best to follow these steps just after doing a fresh install of 14.04 or 14.04.1. (Again, I can't say this enough, but don't do this with a 14.04.2 disk.)
Now, let's get started. Open up a terminal and run the command sudo apt-get update && sudo apt-get install linux-hwe-generic-trusty
. This will install Linux 3.16 and it's kernel headers for you. Now, prepare to test the new kernel! Reboot your system, and your computer should boot into Linux 3.16. The bug should be fixed, and all should be well now. If they are, skip the next paragraph on troubleshooting.
If the above worked for you, great. Move to the next paragraph. If it didn't, gave some unusual errors, prevented you from logging in, or had some other bizarre behavior, you need to reboot your system and remove the kernel. Hold down Shift as your system boots (no need if you dual-boot with GRUB!) and choose "Advanced options" or something similar. Choose the newest Linux 3.13 (recovery mode) and boot that. Choose to get to a root shell or terminal (again, could say something different), and let it load. Then, you must enter the command mount -o remount,rw /
to make your filesystem writeable. If you have multiple partitions for your filesystem, you must also run mount --all
afterwards. (If you're unsure if you do or not, run it anyway.) Then run apt-get purge linux-hwe-generic-trusty && apt-get autoremove
. Reboot your system, and skip the next paragraph (it is meant for those that got the kernel to work).
If you didn't get the kernel to work, skip tot he next paragraph. If you did, you must be lucky, as it makes this much easier. As you now have Linux 3.16 working well, you can remove 3.13 to free yourself some disk space. Run the command sudo apt-get remove linux-generic linux-image-3.13* && sudo apt-get autoremove
. You should be able to reboot your computer and it will still work fine.
Okay, I hope that helped you. If you never got the kernel to work and followed my directions for removing it, you need to backup your files and re-install. It's the best way. However, make sure you use an Ubuntu 14.04.2 or newer installation disk this time! (If you have a 14.04 or 14.04.1 disk, don't think you can just install that and follow my directions. Believe me, it's just better to create a new disk and install 14.04.2. Then you won't have to follow my directions at all!)
Ctrl+Alt+F2
followed byCtrl+Alt+F7
? See if it fix it temporary