Linux – Can’t setup monitor after reconnecting ThinkPad T570 to USB-C dock

arch linuxdocklaptopxrandr

I've got two monitors connected via DisplayPort to the dock. xrandr displays the external monitors as DP1-1 and DP1-2 and the laptop as eDP1.

I set up my monitors with the following in ~/.xprofile:

xrandr --output eDP1 --same-as DP1-1
xrandr --output DP1-2 --right-of DP1-1

This works fine. When disconnecting the laptop from the dock the laptop screen does the right thing, reverting to a single monitor. When reconnecting the laptop DP1-1 shows up, but DP1-2 remains blank. . ~/.xprofile changes nothing, and no error message is printed. I tried reconfiguring using the --crtc option, but all I ended up with were complaints that crtc-1 (or something similar) was not configured correctly. After trying a couple things I got "xrandr: cannot find output 0x46", which I can't find any precedence for.

After reconnecting the monitors have the same names ("DP1-1" and "DP1-2") and both of them are shown as "connected" by xrandr.

Best Answer

In my experience, it sometimes works to issue xrandr --auto after connecting to the dock again. This brings up the external monitor 3 out of 10 times at least. Also logging out and then in brings the monitor back to life.

Related Solutions

How to configure Xorg for a dynamic dual monitor setup

When I've done things like that in the past, the way I accomplished it was by having multiple /etc/X11/xorg.conf files. Then in /etc/rc.local (or equiv), detect your conditions upon starting up and copy the right file into place before the X server is started.

In the end, though, I no longer go this route. It's far easier to do the dynamic xrandr/gui-config hacks these days because they let you do it dynamically not just at boot time and even as you plug and unplug the monitors live. There isn't any xorg.conf settings that refer to dynamically changing connections, for instance.

[oh, and I generally recommend you don't run your laptop with the lid closed. It doesn't cool as well and in the long run you'll likely run into heat-damage issues]

Bash – xrandr: cannot find mode on startup

First add the mode you want.

Use gtf/cvt and xrandr to do that.

$ cvt 1360 768 60
# 1360x768 59.80 Hz (CVT) hsync: 47.72 kHz; pclk: 84.75 MHz
Modeline "1360x768_60.00"   84.75  1360 1432 1568 1776  768 771 781 798 -hsync +vsync
$ gtf 1360 768 60 -x

  # 1360x768 @ 60.00 Hz (GTF) hsync: 47.70 kHz; pclk: 84.72 MHz
  Modeline "1360x768_60.00"  84.72  1360 1424 1568 1776  768 769 772 795  -HSync +Vsync

$ xrandr --newmode "1360x768_60.00"  84.72  1360 1424 1568 1776  768 769 772 795  -HSync +Vsync
$ xrandr --addmode VGA1 "1360x768_60.00"

Best Answer

Related Solutions

How to configure Xorg for a dynamic dual monitor setup

Bash – xrandr: cannot find mode on startup

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