Comment 27 for bug 558569

This does not sound like the issue discussed here. As far as I understand Ubuntu blacklisted viafb and therefore no issues you currently experience can be related to it. Your issue sounds like you can at least figure out where characters are. It would be interesting whether anything is shown correctly during boot process (removing "quiet splash"?). I suggest you look for another bug report that looks like the issue you have or to open one if none exists.

For the issue discussed here:
Thanks to Leo it was possible to narrow it down to the I2C area. As it does not look like a general issue (some of these IGPs do work) I assume that something on the board where it occurs is wired differently. I do not push the (debug) patch to mainline because it can cause regressions and would forbid any auto-detection (of available resolutions and the like). I am trying to improve the code to auto-detect where devices are connected and plan to query only connected devices via I2C (and hope that this will automatically solve this issue) but that takes a while especially as there exists nearly no documentation for older chipsets.