this post was submitted on 26 Jun 2025
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External monitor power management issues (piefed.ca)
submitted 2 days ago by GreatBlueHeron@piefed.ca to c/linux@lemmy.ml
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It feels weird to just jump into a generic Linux community and ask a question. It's nice being so small - kinda like the internet used to be.

Anyway, I've been running Linux servers for decades but only recently switched my desktop. I first tried Debian 12 and I'm now on OpenSUSE Tumbleweed - I switched in the hope of getting newer drivers and maybe fixing this issue.

I have a HP laptop with onboard Intel graphics and an external monitor connected with USB-C. In general it works great - until it doesn't. From time to time the external monitor does not wake up after a suspend. Normally turning the monitor off and back on will cause some sort of driver reset and it comes back. Once or twice this has not helped and I've had to reboot.

I'm running Xorg as Wayland on Tumbleweed won't start on t his machine. Wayland may have worked with Debian, I don't recall. I don't think it's worth listing details of my versions as it's happened on two distros and through a couple of minor updates to Xorg on openSUSE. It happens with KDE or LXDE.

Any suggestions?

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[–] just_another_person@lemmy.world 5 points 2 days ago* (last edited 2 days ago) (2 children)

Few things:

  1. If you use the same USB port for this all the time, disable power saving on that port
  2. Make sure this isn't a PD port (this is a laptop design annoyance)
  3. Make sure your monitor's own power saving settings aren't the issue by disabling things like "deep sleep" or similar

Another thing to try is download Fedora LiveUSB and test it with that (it will be Wayland). If it works, then you know it's a config issue with your distro.

[–] GreatBlueHeron@piefed.ca 1 points 2 days ago (1 children)
  1. If you use the same USB port for this all the time, disable power saving on that port

I use the same port all the time. I want power saving on the port. I like to just get up from my PC and have it go to sleep by itself and wake back up when I come and jiggle the mouse. It's working exactly as I would like maybe 90% of the time. Just sometimes the external monitor doesn't wake up.

  1. Make sure this isn't a PD port (this is a laptop design annoyance)

It is a PD port, and it is powering the laptop. I'm not sure why this would be a problem? It's worked fine for 5-6 years with Windows and works 90% of the time now with Linux.

  1. Make sure your monitor's own power saving settings aren't the issue by disabling things like "deep sleep" or similar

Again, I'm not sure how this could be a problem for the scenario I describe. The settings work fine 90% of the time. It's not even time related: sometimes I can come to it first thing in the morning, after it's been asleep all night, and it wakes perfectly; sometimes I can get up to go get a glass of water and come back and the external monitor won't wake up. It seems totally random.

[–] just_another_person@lemmy.world 3 points 2 days ago
  1. Power saving features may not fire on changing from sleep states. This happens on Windows as well, but the power management system in Windows disables power saving features of the port when a display is detected. In Linux you want this off for the same reasons. It doesn't prevent the machine from sleeping.
  2. On waking, PD ports can cause issues with negotiation of the signal reset and changemode for displays.
  3. Monitors communicate their power status over USB-C, so when your machine wakes up, it may try to fire an event that says "wake up" to the monitor, but if the monitor isn't in a state where it's expected a signal (deep sleep), then it won't wake up.

Any one of these could be the issue, but if you don't want to take steps to debug it, then just unplugging and replugging the cable will kick the monitor back up.