I'm trying to list the connected monitors using xrandr that is returning the following information:

Screen 0: minimum 320 x 200, current 1366 x 768, maximum 8192 x 8192
eDP-1 connected primary 1366x768+0+0 (normal left inverted right x axis y axis) 344mm x 193mm
   1366x768      60.06*+
   1360x768      59.80    59.96  
   1280x720      60.00    59.99    59.86    59.74  
   1024x768      60.04    60.00  
   960x720       60.00  
   928x696       60.05  
   896x672       60.01  
   1024x576      59.95    59.96    59.90    59.82  
   960x600       59.93    60.00  
   960x540       59.96    59.99    59.63    59.82  
   800x600       60.00    60.32    56.25  
   840x525       60.01    59.88  
   864x486       59.92    59.57  
   800x512       60.17  
   700x525       59.98  
   800x450       59.95    59.82  
   640x512       60.02  
   720x450       59.89  
   700x450       59.96    59.88  
   640x480       60.00    59.94  
   720x405       59.51    58.99  
   684x384       59.88    59.85  
   680x384       59.80    59.96  
   640x400       59.88    59.98  
   576x432       60.06  
   640x360       59.86    59.83    59.84    59.32  
   512x384       60.00  
   512x288       60.00    59.92  
   480x270       59.63    59.82  
   400x300       60.32    56.34  
   432x243       59.92    59.57  
   320x240       60.05  
   360x202       59.51    59.13  
   320x180       59.84    59.32  
DP-1 disconnected (normal left inverted right x axis y axis)
HDMI-1 disconnected (normal left inverted right x axis y axis)

But I don't know why the VGA port was labeled as DP-1 instead of VGA-1, while the HDMI port was clearly labeled as HDMI-1.

So does the Linux kernel label the VGA, DVI and DisplayPort ports as "DP"?


This answer on AskUbuntu seems relevant to your question.

Basically, the VGA port you see is just a built-in adapter for the native DP port.

In this case, xrandr correctly shows you the installed hardware which is a DisplayPort.

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  • Thanks for your answer. Is there any available Linux documentation which provides an information about the names of the different video ports: such as DVI, VGA ..? – user6039980 Sep 4 '18 at 10:07
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    @Kais sorry, a quick search didn't show up anything about a list, but there should be something in xrandr or kernel source code. – Mr Shunz Sep 4 '18 at 10:16
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    The name scheme depends on the graphics driver, and every driver uses names however it wants to. However, usually the names are easily recognizable. – dirkt Sep 4 '18 at 10:57

If that particular graphics chip (or in case of an iGPU, that system chipset) was originally designed to be used in laptops, it might have three outputs in the actual chip: an embedded DisplayPort (eDP) for the laptop's built-in display, then a regular HDMI and DisplayPort for external connections.

The designer of your system/motherboard is free to either use them as originally designed, or to add converters to provide other types of connectors.

The MXM graphics module standard includes a standard definition for an ACPI/WMI table that can be used to describe the types and locations of display connectors. However, if the firmware development team was in a hurry, they might have just used the standard example data table from the GPU vendor, instead of customizing it to match the actual hardware.

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