Comment 33 for bug 768184

$ cat /sys/kernel/debug/dri/0/i915_error_state
no error state collected

That's after a restart of the X server (Ctrl-Alt-Bcksp) so that I can access the machine again; I assume that would not reset i915_error_state?

The only indication in the logs I can see is in /var/log/Xorg.0.log:

[ 259.306] (WW) intel(0): flip queue failed: Invalid argument
[ 259.306] (WW) intel(0): Page flip failed: Invalid argument
[ 260.299] (WW) intel(0): flip queue failed: Device or resource busy
[ 260.299] (WW) intel(0): Page flip failed: Device or resource busy
[last two lines repeating]

These start occurring after I enable an output using xrandr (after a suspend/resume cycle); Xorg works for a while, but hangs immediately after I switch to a text console and back to X (a required action to actually see something via the new output, as per https://bugzilla.kernel.org/show_bug.cgi?id=24982).

A workaround that works for me is to modify xf86-video-intel to force intel->use_pageflipping to FALSE. I believe there used to be a user-accessible option to turn it off, but it's been removed? That is rather unfortunate, I must say.