Hey, I did a bisection on my lenovo W500 (almost same hardware as T500) and it turns out that the bug was introduced in 2.6.37-2.9 natty kernel, and made it's way back to maverick with 2.6.38-10.44 update. After that I bisected a vanilla kernel, and it turns out that the offending commit is: [ba032a58d1f320039e7850fb6e8651695c1aa571] drm/radeon/kms: rework spread spectrum handling so it is a bug with spread spectrum handling on displayport. This feature was disabled on DP and HDMI prior to that commit.
It seems that this is already reported to radeon/kernel guys here: https://bugs.freedesktop.org/show_bug.cgi?id=40699 I'm gonna provide more details there. ** Bug watch added: freedesktop.org Bugzilla #40699 https://bugs.freedesktop.org/show_bug.cgi?id=40699 -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/952486 Title: 1002:9591 [Lenovo ThinkPad T500] External monitor on display port has no sync with radeon driver To manage notifications about this bug go to: https://bugs.launchpad.net/linux/+bug/952486/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
