Created attachment 140381 [details]
journalctl -k output
i am using a "[AMD/ATI] Barts XT [Radeon HD 6870]" card on an Arch Installation with Kernel 3.15.1.
If i append "radeon.dpm=1" to the kernel parameters i can boot fine into KDM. But at the login process (KDE) Xorg freezes. I can still move the mouse pointer and the SysRQ Keys are also working.
Sometimes, after i press SysRQ + K i can manage to get back to KDM and start another login attempt. And in some cases i can login completely and work in a stable environment.
I attached the output of "journalctl -k" after getting back to KDM with SysRQ+K.
Right now i am building linux-git from AUR.
Kernel build from git doesn't help.
The freeze seems to be related to the hdmi audio output. If i blacklist the snd_hda_intel and the snd_hda_codec_hdmi modules the system is running fine (at least for my first try).
Unfortunately my onboard sound card is also blacklisted with these modules.
Instead of blacklisting the kernel modules, adding radeon.audio=0 to the kernel parameters also helps.
For me this is a workaround as i don't need the hdmi audio output.
Duplicate of bug 68571.