With the proprietary nvidia drivers, suspend fails if I try to suspend while the connected monitors are powered off

[Martin]

As the title says, I'm unable to suspend if I have monitors connected which don't have power. I hit the suspend button (or run `pm-suspend`), and the computer just becomes unresponsive, stops reacting to input, shows nothing on the screen (if I turn the monitors on again), is unreachable through SSH, but the fans are still running, LEDs still glowing, and it can't be waken up by any other means than a force restart through cutting power or holding down the power button.

I followed this guide to debug this problem: https://wiki.ubuntu.com/DebuggingKernelSuspend - the relevant part of the dmesg output is:

[ 0.756829] PM: Magic number: 0:484:522
[ 0.756830] PM: hash matches drivers/base/power/main.c:1598
[ 0.756849] pci 0000:07:00.0: hash matches

That 0000:07:00.0 device is my nvidia GPU (a GTX 1080Ti).

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1. Which part of the process does the issue occur with, the suspend to ram, or resuming from?

The issue seems to happen during suspend. I believe this because during a normal
suspend, the GPU's RGB LEDs will turn off while the machine is suspended,
but when this issue occurs, the GPU's RGB LEDs stay on. (I knew those RGB LEDs
would come in useful some day!)

2. Please advise how you suspended specifically.

While reproducing the issue for this bug report, I've been using `pm-suspend`.
But it also happens when clicking the suspend button on my keyboard.

3. Please advise how you resumed specifically.

When this issue occurs, I can't resume. I hold the power button in until the system
powers off and then I boot as normal.

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I'm unable to respond to the points which require running the latest kernel, since the proprietary drivers don't seem to work on the latest kernel (or maybe they're running in some form of fallback mode? I see a 640x480 output on one of my monitors).

And, as a final note, I'm sorry about this bug report. I know there's probably nothing anybody can do about a bug in the proprietary drivers. That sucks. I wish we didn't have to deal with bad proprietary graphics drivers anymore. But I figured it's better to report the issue than to not report it.

ProblemType: Bug
DistroRelease: Ubuntu 21.04
Package: nvidia-driver-470 470.57.02-0ubuntu0.21.04.1
ProcVersionSignature: Ubuntu 5.11.0-25.27-generic 5.11.22
Uname: Linux 5.11.0-25-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.20.11-0ubuntu65.1
Architecture: amd64
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Sun Aug 8 23:03:57 2021
InstallationDate: Installed on 2021-06-10 (59 days ago)
InstallationMedia: Ubuntu 21.04 "Hirsute Hippo" - Release amd64 (20210420)
SourcePackage: nvidia-graphics-drivers-470
UpgradeStatus: No upgrade log present (probably fresh install)