Switch graphics mode without reboot

[crawfxrd]

By further utilizing gpu-manager, we can perform most operations for switching graphics modes without requiring a reboot.

In order for switching and runpm to work correctly, GDM must be restarted. This will end all running GNOME sessions.

system76-power graphics <mode>
systemctl restart display-manager

See: #57

[gase12]

hi whats up with the review? :)

[flukejones]

Hey thanks for doing this!

[leviport]

I began testing this and it's looking good, but it's definitely a WIP at the moment. Here is what I'm seeing:

• As @crawfxrd specified, switching from Intel to either Nvidia or Hybrid after a logout/login seems to work pretty well. The first switch seemed very reliable, with subsequent switches sometimes getting more error-prone.

• When switching from Hybrid to Nvidia at one point (I lost track of how many other switches preceded this switch), I logged out and back in again and saw that all gnome extensions had been disabled.

• I was able to switch from either Nvidia or Hybrid to Intel by restarting GDM with systemctl restart display-manager, but switching then from Intel to Hybrid/Nvidia without restarting resulted in a hang at the "Switching graphics modes" window, and that window never changed to the version with "restart now" and "restart later" buttons.

• All of the messaging and dialogs still point to restarting after a switch, so that will all need to be updated eventually as well.

Once we're further along, we can start doing some more testing!

[isantop]

I would imagine we want to have the messaging and dialog restart the session/GDM for the user. We can probably co-opt the current reboot dialog for that.

[crawfxrd]

Need to investigate runpm. I'm seeing the card left active after switching from Intel to hybrid.

---

Restarting GDM fixes it. Not sure why it interferes with runpm.

[crawfxrd]

@leviport I haven't been able to reproduce the issues. I'd be interested in getting any logs for the hang if you're able to repro it.

Remaining work for #57 is:

• restart GDM
• apply run-time power management workarounds
• integrate with the shell extension

[leviport]

I'd be interested in getting any logs for the hang if you're able to repro it.

I can take another look to see if I can make it happen again, though it looks like the latest eoan build didn't succeed. Once it builds again I will see if it's still an issue and gather logs if it is.

[crawfxrd]

gpu-manager is configured to run before display-manager, so implementing a display-manager restart would allow this call to be removed.

[lzyang2000]

Great feature, hope it gets merged soon.
I definitely do not want to reboot every time I switch graphics lol
Thanks for all the work!

[brs17]

@crawfxrd are we expecting this to function in 18.04 (between Intel and NVIDIA modes)?

[crawfxrd]

It looks like the required logic exists in ubuntu-drivers-common for 18.04. I don't see why it wouldn't work, but I didn't consider it.

[lzyang2000]

Any plans to merge this

[brs17]

I have been unable to recreate the issues seen previously. This looks good to me.

Things to note going forward:

• We should backport this to master_bionic as well Backport switching graphics without reboot to bionic #135 (if possible).
• There should be frontend updates to expose this in the gnome-shell extension Support graphics switching without reboot gnome-shell-extension-system76-power#34

[crawfxrd]

Because this can't be implemented cleanly (must kill all X sessions), we're going to keep requiring a reboot. Steps in #57 will still work.