I’ve been in the habit of hibernating my system rather than suspending since suspending has in the past been unreliable. But this afternoon, I decided to live dangerously and suspend it as an experiment. It wouldn’t wake up, had to restart. Okay, know there’s a problem here, but I know how to get around it: hibernate instead of suspend.
When it restarted, my second monitor would not come up. The screen was white. I tried a few things, plug/unplug, power the monitor on and off. None of that helped. I guess I really didn’t expect it to.
The Settings->Displays tab would only display the laptop monitor, not the second monitor.
xrandr agreed with Settings->Displays : only one monitor.
Googling around brought me to the idea that reinstalling nVidia drivers might be indicated.
But before I did that, I decided to check the Software and Updates->Additional Drivers screen. What a shock!
Instead of the nvidia-driver-535 (proprietary) driver I had had previously, It was now using the X.Org X server - Nouveau display driver, which I vaguely remember being responsible for my last dual monitor snafu.
So I switched back to proper driver and it told me I had to reboot the system. But it kept flashing the same error messages over and over and would not reboot.
So, I restarted the machine with the Magic-Sysrq sequence and when it came back up, sanity had been restored, both monitors worked like a charm, in spite of those error messages.
This raises several questions:
1) What the heck could be going on in the suspend process that would force the correct nVidia driver to be removed? And why would that not happen in the hibernate process?
2) The error messages do indicate that the nouveau driver was their cause but the solution was much simpler than what the error messages said - just reboot the #@$%^& thing. I suppose “unloading the conflicting kernel module” would happen in a reboot.
What a world! But all’s well that ends well, I suppose.