[X1] Turn off the display when system is suspended

[vunnyso]

• Addresses SP-4844 - Display turns on in sleep mode when the lid is closed.

Description of changes

Checklist for things done

• Summary of the proposed changes in the PR description
• More detailed description in the commit message(s)
• Commits are squashed into relevant entities - avoid a lot of minimal dev time commits in the PR
• Contribution guidelines followed
• Ghaf documentation updated with the commit - https://tiiuae.github.io/ghaf/
• PR linked to architecture documentation and requirement(s) (ticket id)
• Test procedure described (or includes tests). Select one or more:
  • Tested on Lenovo X1 x86_64
  • Tested on Jetson Orin NX or AGX aarch64
  • Tested on Polarfire riscv64
• Author has run nix flake check --accept-flake-config and it passes
• All automatic Github Action checks pass - see actions
• Author has added reviewers and removed PR draft status

Testing

• Display will get turn off automatically when lid is closed.
• Display will get turn off automatically when we run sudo systsemctl suspend on ghaf-host

Known issues with Qemu

1. As persistent Storage is enabled in gui-vm due to which gui-vm fails to suspend as virtio filesystem doesn't support suspend, details here.

gui-vm kernel: virtio-fs: suspend/resume not yet supported
gui-vm kernel: virtio-pci 0000:00:04.0: PM: pci_pm_suspend(): virtio_pci_freeze+0x0/0x50 [virtio_pci] returns -95
gui-vm kernel: virtio-pci 0000:00:04.0: PM: dpm_run_callback(): pci_pm_suspend+0x0/0x170 returns -95
gui-vm kernel: virtio-pci 0000:00:04.0: PM: failed to suspend async: error -95

2. If someway we can managed to solve problem 1, then gui-vm cannot be resume on keyboard press, way to resume is from qemu monitor socket.

3. If someway we can managed to solve problem 2, then qemu freezes after resume, more details here

So considering above qemu issues, I think better to turn off display.

Power improvements

Check	With PR	Without PR
Battery Drainage	~2 % per hour	~8 % per hour

Approx 4 times improvement in battery life when lid is closed.

Next Steps

Try to replicate with givc service if feasible.

[nesteroff]

I was thinking that maybe we don’t need to suspend the GUIVM at all. Instead, we can simply turn off the display before suspending and turn it back on after resuming using the wlopm command.
These commands can be added to a oneshot systemd service that runs before and after the sleep.target target on the host. We can use SSH to execute them in the GUIVM from the host, or better yet add them to the RPC service.
This way, we don’t need to take care of the QEMU and virtiofs suspend/resume issues. Also, we will be able to remove the -device button from here.
Here’s an example of how to turn the display on and off from the host (pkgs.wlopm needs to be added to the GUIVM):

ssh -t ghaf@gui-vm-debug 'WAYLAND_DISPLAY=/run/user/1000/wayland-0 wlopm --off \*’
ssh -t ghaf@gui-vm-debug 'WAYLAND_DISPLAY=/run/user/1000/wayland-0 wlopm --on \*’

@vunnyso what do you think?

[vunnyso]

I was thinking that maybe we don’t need to suspend the GUIVM at all. Instead, we can simply turn off the display before suspending and turn it back on after resuming using the wlopm command. These commands can be added to a oneshot systemd service that runs before and after the sleep.target target on the host. We can use SSH to execute them in the GUIVM from the host, or better yet add them to the RPC service. This way, we don’t need to take care of the QEMU and virtiofs suspend/resume issues. Also, we will be able to remove the -device button from here. Here’s an example of how to turn the display on and off from the host (pkgs.wlopm needs to be added to the GUIVM):

ssh -t ghaf@gui-vm-debug 'WAYLAND_DISPLAY=/run/user/1000/wayland-0 wlopm --off \*’
ssh -t ghaf@gui-vm-debug 'WAYLAND_DISPLAY=/run/user/1000/wayland-0 wlopm --on \*’

@vunnyso what do you think?

Thanks @nesteroff for suggestion, I think its good idea to start with, as I am still struggling to find proper fix from qemu