I'm able to get the internal display back to normal by restarting the X server from a text console.
At all points I've checked (before connecting external display, after connecting external display, after switching to text console, after restarting X) the i915_error_state sysfs file reads "no error state collected"
I'm able to get the internal display back to normal by restarting the X server from a text console.
At all points I've checked (before connecting external display, after connecting external display, after switching to text console, after restarting X) the i915_error_state sysfs file reads "no error state collected"