Thunderbolt Apple Display Not Waking Mac Mini Running Linux (Devuan)
If you have a Mac Mini with two monitors attached, one through a Thunderbolt port and another through an HDMI port using an HDMI-to-VGA adapter, you may encounter issues with the Thunderbolt display not waking up when using Linux (Devuan). This article will provide a detailed explanation of the issue and potential solutions.
Understanding the Issue
The issue arises due to the way the Mac Mini handles the two displays. The Thunderbolt display is recognized as a "hot-pluggable" device, while the HDMI display is not. This means that the Thunderbolt display can be connected and disconnected while the system is running, while the HDMI display cannot. This can cause issues when trying to wake the Thunderbolt display after it has gone to sleep.
Checking the Display Settings
The first step in troubleshooting this issue is to check the display settings. To do this, open the "Display" settings in the Devuan control panel. Make sure that both displays are recognized and that the correct resolution is set for each one.
Checking the xrandr Output
To get a more detailed view of the display settings, you can use the xrandr command. This command will show you the current resolution and refresh rate for each display, as well as any connected displays that are not currently active. The output should look something like this:
Screen 0: minimum 320 x 200, current 3840 x 1080, maximum 16384 x 16384
eDP-1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 293mm x 165mm
1920x1080 60.00\*+ 59.93
DP-1 connected 1920x1200+1920+0 (normal left inverted right x axis y axis) 518mm x 324mm
1920x1200 60.00\*+
HDMI-1 disconnected (normal left inverted right x axis y axis)
VGA-1 connected 960x540+3840+0 (normal left inverted right x axis y axis) 344mm x 194mm
960x540 60.00\*
Forcing the Thunderbolt Display to Wake
If the Thunderbolt display is still not waking up, you can try forcing it to wake by using the xrandr command. To do this, first identify the name of the Thunderbolt display (in this example, it is DP-1). Then, use the following command to force the display to wake:
xrandr --output DP-1 --auto
Persistent Configuration
To make the changes persistent, you can create a script that runs the xrandr command at startup. To do this, create a file called startup.sh in the /etc/X11/Xsession.d/ directory with the following contents:
#!/bin/bash
xrandr --output DP-1 --auto
Then, make the script executable by running the following command:
sudo chmod +x /etc/X11/Xsession.d/startup.sh
References
- Apple: Connect multiple displays to your Mac mini
- Devuan: Display Manager
- Arch Linux: Xrandr
This article provided an in-depth explanation of the issue with the Thunderbolt Apple display not waking up when using Linux (Devuan) on a Mac Mini with two monitors attached. By following the steps outlined in this article, you should be able to resolve the issue and have both displays working properly.