OK, about the bisect: c2fb3094669a3205f16a32f4119d0afe40b1a1fd is the first bad commit Date: Sun Apr 20 13:24:32 2014 +0200
drm/radeon: improve PLL limit handling in post div calculation This improves the PLL parameters when we work at the limits of the allowed ranges. I reverted this commit (I got some good working tips from Chris Bainbridge), tested the result with the kernels 4.4.0-rc1 and 4.6.0-rc6+ and the problem is completely gone. I ended up with a good stable and rock-solid display output without artefacts. I could test against some other kernels if any of the devs here would like me to do that. -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1479136 Title: [ubuntu 14.04.2] Artefacts in radeon driver on kernel 3.16 and upwards Status in linux package in Ubuntu: Confirmed Bug description: Ubuntu-Mate 14.04.2 This is what I get if I run a kernel newer than 3.13: https://www.youtube.com/watch?v=nx2-Fvihzxg sorry for the link, I just don't know how to describe these artefacts verbally. (a storm of small horizontal moving blips from right to left ??) Those artefacts appear as soon as new kernel is selected in GRUB, and remain during the whole session. The lastest kernel (from the main repository that is) working without artifacts is v3.13.0.59. All later kernels have artifacts. All later kernels also are either "-utopic" or "-vivid" instead of "-trusty", but I do not know if it is related. GPU: Mobility Radeon HD 3200 (RS780M) System: Ubuntu Mate 14.04.2 32-bit Kernels tested: 3.13.0.59 (and earlier) , 3.16.0.45 , 3.19.0.25 Only 3.13.0.59 (and earlier) are without problems. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1479136/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp