Immediately after it hangs:
* $ sudo cat /sys/kernel/debug/dri/0/i915_error_state
no error state collected
* 'DISPLAY=:0.0 xrandr' seems to work.
'DISPLAY=:0.0 xrandr --output LVDS1 --auto --output HDMI2 --off' turned off the monitor, but then never returned.
* 'DISPLAY=:0.0 gnome-terminal' just hangs
* when screen dims due to idle (which i've set to 2 minutes), keyboard input will brighten the screen again.
then I tried 'sudo stop lightdm', and slept 120 seconds.
Still, no error state in 'i915_error_state'
Then, i tried 'chvt 1', and gave it 120 seconds to return.
at this point 'dmesg' shows the trace, but /i915_error_state still says "no error state collected"
Immediately after it hangs: debug/dri/ 0/i915_ error_state
* $ sudo cat /sys/kernel/
no error state collected
* 'DISPLAY=:0.0 xrandr' seems to work.
'DISPLAY=:0.0 xrandr --output LVDS1 --auto --output HDMI2 --off' turned off the monitor, but then never returned.
* 'DISPLAY=:0.0 gnome-terminal' just hangs
* when screen dims due to idle (which i've set to 2 minutes), keyboard input will brighten the screen again.
then I tried 'sudo stop lightdm', and slept 120 seconds.
Still, no error state in 'i915_error_state'
Then, i tried 'chvt 1', and gave it 120 seconds to return.
at this point 'dmesg' shows the trace, but /i915_error_state still says "no error state collected"