Testing and Troubleshooting: Linux Source Device

read-edid

• get-edid man page
• parse-edid man page
• read-edid home page

$ sudo apt-get install read-edid
...
$ sudo get-edid | parse-edid 

xrandr

On Linux you can use xrandr to see if the display is correctly detected.

xrandr example output

In the below example the LVDS1 is the internal screen.

The HDMI2USB is connected to DisplayPort port on a X220 Laptop via a [DisplayPort to HDMI adapter]. As this device has a DP++ port, this configuration appears as HDMI1 rather than DP1. (In this configuration the [DisplayPort to HDMI adapter] is a passive device and the conversion is happening in your computer!)

# xrandr
LVDS1 connected primary 1366x768+0+0 (normal left inverted right x axis y axis) 277mm x 156mm
   1366x768       60.0*+
   1360x768       59.8     60.0  
   1024x768       60.0  
   800x600        60.3     56.2  
   640x480        59.9  
VGA1 disconnected (normal left inverted right x axis y axis)
HDMI1 connected 1024x768+1366+0 (normal left inverted right x axis y axis) 0mm x 0mm
   1024x768       60.0*+
DP1 disconnected (normal left inverted right x axis y axis)
HDMI2 disconnected (normal left inverted right x axis y axis)
HDMI3 disconnected (normal left inverted right x axis y axis)
DP2 disconnected (normal left inverted right x axis y axis)
DP3 disconnected (normal left inverted right x axis y axis)
VIRTUAL1 disconnected (normal left inverted right x axis y axis)
#