显示器已停止接收输入。已连接并注册，但没有显示

Question

一夜之间，我左侧的显示器不显示。它似乎已连接并注册到显示管理器，但没有信号通过。

我现在使用 lightdm 作为显示管理器，刚刚从 18.04 升级到 18.10，希望这会有所帮助。问题依然存在。我尝试过更改分辨率，但要么没有区别，要么显示未找到：

$ xrandr --output DP-2 --mode 1920x1080 --output DP-1 --mode 1920x1080 --same-as DP-2
xrandr: cannot find mode 1920x1080

有人有什么想法吗？

xrandr 输出：

Screen 0: minimum 320 x 200, current 2944 x 1080, maximum 8192 x 8192
DP-1 connected 1024x768+0+0 (normal left inverted right x axis y axis) 531mm x 299mm
   1024x768      60.00* 
   800x600       75.00    60.32  
   720x576       50.00    50.00    50.00  
   720x480       60.00    60.00    59.94    59.94    59.94  
   640x480       75.00    72.81    66.67    60.00    59.94    59.94  
   720x400       70.08  
HDMI-1 disconnected (normal left inverted right x axis y axis)
DP-2 connected primary 1920x1080+1024+0 (normal left inverted right x axis y axis) 531mm x 299mm
   1920x1080     60.00*+  60.00    50.00    59.94  
   1920x1080i    60.00    50.00    59.94  
   1680x1050     59.95  
   1280x1024     75.02    60.02  
   1440x900      74.98    59.89  
   1280x720      60.00    60.00    50.00    50.00    59.94  
   1024x768      75.03    60.00  
   800x600       75.00    60.32  
   720x576       50.00    50.00    50.00  
   720x480       60.00    60.00    59.94    59.94    59.94  
   640x480       75.00    72.81    66.67    60.00    59.94    59.94  
   720x400       70.08  
HDMI-2 disconnected (normal left inverted right x axis y axis)
DP-3 disconnected (normal left inverted right x axis y axis)
HDMI-3 disconnected (normal left inverted right x axis y axis)