Cfrgtkky

I have a MacBook Pro 2011 (8,2) which suffers from the infamous graphic card problems. I've successfully installed Xubuntu 18.10 by disabling the Radeon graphic card via Grub and EFI partion.

I am trying to connect an external display via Mini Display Port, but the monitor is not detected. I tried an Mini Display Port <--> to Display Port cable (directly to the monitor's display port) an a series of adapters (Mini Display Port <--> VGA <--> HDMI). In both cases the monitor detects the cable and says "no signal from computer".

Is there anything how I could further debug this?

$ xrandr 

Screen 0: minimum 320 x 200, current 1680 x 1050, maximum 8192 x 8192

LVDS-1 connected primary 1680x1050+0+0 (normal left inverted right x axis y axis) 331mm x 207mm

   1680x1050     59.88*+

   1600x1024     60.17  

   1400x1050     59.98  

   1600x900      59.99    59.94    59.95    59.82  

   1280x1024     60.02  

   1440x900      59.89  

   1400x900      59.96    59.88  

   1280x960      60.00  

   1440x810      60.00    59.97  

   1368x768      59.88    59.85  

   1360x768      59.80    59.96  

   1280x800      59.99    59.97    59.81    59.91  

   1152x864      60.00  

   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  

VGA-1 disconnected (normal left inverted right x axis y axis)

HDMI-1 disconnected (normal left inverted right x axis y axis)

DP-1 disconnected (normal left inverted right x axis y axis)

The integrated graphic card of these MacBooks seems not to be able to send images to an external display, i.e. there does not seem to be an software solution unfortunately (that means this question is actually not Ubuntu related). An USB to HDMI adapter (external graphic card) might be able to do the job and of course and a repair of the logic board too.

This is my conclusion after reading this long thread where several people confirm that external displays are not working:

What happens if you connect external display?

Its my understanding the display port connector is hardwired to the dGPU so you cannot use the iGPU to drive an external monitor.

Source

...that it won't be able to do things it should, like run an external monitor...

Source

The other thing I have noticed is not being able to use external display. I ordered a USB to VGA converter, and hopefully that will let me use the external monitor again.

Source