I am running Slackware Linux on my laptop with ATI/AMD Mobility Radeon HD 3670.
I have a recurring crash/lockup that happens intermittently while running X:
my screen will spontaneously freeze for a few seconds, then the screen goes
blank black or white, or slowly change colors, for a few seconds, during which
it's still frozen (mouse/keyboard input has no effect, even CTRL-ALT-F1 or
CTRL-ALT-BACKSPACE). Afterwards it returns me to a distorted/garbled version
of my desktop, and I can switch to a virtual terminal and kill X or reboot.
Sometimes instead -- rarely -- the system recovers successfully and I am
returned to a fully functional X desktop after the lockup. I have saved dmesg
from both versions of the crash.
I haven't figured out a way to trigger it. The only common thread I've noticed
is it seems to only happen when the system is under some kind of load, and is
updating the display. But it happens fairly regularly, something like once a
week.
I have tried adjusting some X radeon settings (man radeon), and some kernel
radeon settings (modinfo radeon). After I added dpm=0 to radeon module
parameters, the crash behavior became more simple and consistent (now it's
almost always a slow fade to white followed by a glitched desktop screen) and
showed closer to a full recovery. Nothing I've tried has stopped the lockup
from occurring entirely, except disabling kernel modesetting (which leaves me
with poor resolution options).
root@Dell-XPS:~# uname -a
Linux Dell-XPS 4.1.15 #2 SMP Tue Dec 15 21:00:31 CST 2015 x86_64 Intel(R)
Core(TM)2 Duo CPU P8600 @ 2.40GHz GenuineIntel GNU/Linux