I'm experiencing flickering and artifacts on my HP Compaq nc8430 with ATI Mobility Radeon X1600 under ArchLinux with kernel 3.16.3-1. This bug is in my opinion not mesa/dri/x11 related, because it does the same even in linux console framebuffer. There might be a problem with PLL or dynamic clock changing, but I tried every possibility and none of them does prevent (for ex. disabling dynclks). Unfortunately I cannot attach the video here (exceeds 5MB limit), so it can be seen here: http://www.youtube.com/watch?v=xSI5G_b82KE Other OS works great including GPU acceleration, so it's not hardware bug, also after a series of rebooting it works sometimes without this bug (1 time on 5 tries for example). It does the same without X server, under bare minimum console. Also the speed of flickering varies from time to time, it can flicker lightly but sometimes it does very fast. I would like to continue using this notebook under Linux, but in this state it's not usable. If there are more informations needed please write and I'll try to attach them. Thanks in advance.
Also I would add that linux-lts it's a 3.14.19-1 kernel is working ok, so it's a regression but I don't know which info I would need to provide for somebody to help me with this.
Same case here https://bugzilla.redhat.com/show_bug.cgi?id=1241579
I run into this today after installing Ubuntu 15.10 on a HP nc8430 with the X1600 graphic card. I'll try to install a 3.14 kernel and see if it works.
Just in case anybody not familiar with dealing with multiple kernels runs into this bug, I followed the instructions of https://wiki.ubuntu.com/Kernel/MainlineBuilds (I'm on Ubuntu). Details of my case: I selected the kernel in http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.14.56-utopic/ which is the latest 3.14 kernel at the time of writing. I downloaded the two generic amd64.deb files (headers and image) plus the linux-headers-3.14.56-031456_3.14.56-031456.201510262131_all.deb file in an empty directory. Then I installed them with sudo dpkg -i * I also had to install this but you might already have it sudo apt-get install module-init-tools Installing module-init-tools restarted the installation of the kernel from where an error due to that package being missing interrupted it. So far the screen looks good but sometimes it was good for a while even with the newer kernel. I'll have to wait and see.
I did not check if this defect was fixed in kernels newer than 4.1. If it is still not, I believe this information is useful. I reduced the interval of the linux kernel’s commits responsible for the bug introduction as follows. $ git log --oneline c9eaa44..a798c10 drivers/gpu/drm/radeon/ a42892e Merge branch 'drm-next-3.15-wip' of git://people.freedesktop.org/~deathsimple/linux into drm-next bcddee2 drm/radeon/ci: make sure mc ucode is loaded before checking the size 8c79bae drm/radeon/si: make sure mc ucode is loaded before checking the size f8a2645 drm/radeon: improve PLL params if we don't match exactly v2 74073c9 drm/radeon: memory leak on bo reservation failure. v2 681941c drm/radeon: fix VCE fence command 7e1858f drm/radeon: re-enable mclk dpm on R7 260X asics 277babc drm/radeon: add support for newer mc ucode on CI (v2) 1ebe928 drm/radeon: add support for newer mc ucode on SI (v2) 5fb9cc4 drm/radeon: apply more strict limits for PLL params v2 6abc6d5 drm/radeon: update CI DPM powertune settings 90c4cde drm/radeon: fix runpm handling on APUs (v4) 57700ad drm/radeon: disable mclk dpm on R7 260X 8902e6f drm/radeon: Improve vramlimit module param documentation be0949f drm/radeon: fix audio pin counts for DCE6+ (v2) 379dfc2 drm/radeon/dp: switch to the common i2c over aux code 25377b9 drm/radeon/dp: handle zero sized i2c over aux transactions (v2) Due to an unrelated hardware problem on my laptop I am unfortunately unable to go further in tracking down the problem. Good luck!