Fedora 27 loses external Thunderbolt display after boot

asked 2018-02-03 09:13:13 -0500

twic gravatar image

I have a display (actually a projector) plugged into a MacBook Pro via its Thunderbolt port and a Thunderbolt-to-HDMI adaptor. When the machine boots with the display plugged in, it detects it; it displays the disk encryption prompt on both the laptop's internal display and the external display, and then displays the Fedora logo on both. However, at some point during boot, it stops using the external display, which goes to a 'no signal' state.

Once the machine is booted and i have logged in, i have tried unplugging and replugging the cable, and pressing 'detect displays' in the Displays control panel, all to no avail.

I'm running fully-updated Fedora 27, with kernel 4.14.16-300.fc27.x86_64. I've tried rebooting onto an older kernel, 4.14.13-300.fc27.x86_64, but i see the same behaviour. The external display worked a couple of weeks ago, and i don't know exactly what updates i've applied since then. I haven't made any changes to the graphics configuration.

I am running Cinnamon as a desktop environment. The laptop has hybrid graphics, but i believe i am only using the integrated graphics part of it, as i have had trouble getting switching set up.

I have another laptop, a Dell XPS 15 running Ubuntu 16.04 with kernel 4.4.0-104-generic, which detects and drives the display directly via HDMI without any trouble.

There's nothing obviously wrong in dmesg, although i'm not confident i would spot it if there was. No new entries appear when i unplug and replug the cable. dmesg and lspci both report the existence of the Thunderbolt controller. xrandr says:

$ xrandr -q
Screen 0: minimum 320 x 200, current 1680 x 1050, maximum 8192 x 8192
LVDS-2 connected primary 1680x1050+0+0 (normal left inverted right x axis y axis) 331mm x 207mm
   1680x1050     59.88*+
   1400x1050     59.98  
   1280x1024     60.02  
   1280x960      60.00  
   1024x768      60.04    60.00  
   960x720       60.00  
   928x696       60.05  
   896x672       60.01  
   800x600       60.00    60.32    56.25  
   700x525       59.98  
   640x512       60.02  
   640x480       60.00    59.94  
   512x384       60.00  
   400x300       60.32    56.34  
   320x240       60.05  
VGA-1 disconnected (normal left inverted right x axis y axis)
HDMI-1 disconnected (normal left inverted right x axis y axis)
DP-4 disconnected (normal left inverted right x axis y axis)

vgaswitcheroo confirms i am on integrated graphics:

$ lspci | grep VGA
00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09)
01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Whistler [Radeon HD 6630M/6650M/6750M/7670M/7690M] (rev ff)
$ sudo cat /sys/kernel/debug/vgaswitcheroo/switch
0:DIS: :Off:0000:01:00.0
2:DIS-Audio: :Off:0000:01:00.1

Any idea what might be wrong, or how i should investigate this?

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I'm having a very similar situation. I'll be opening an issue, so I won't give all the details here other than to say:

I run a Lenovo P50 laptop. It worked fine with kernel 4.13.16-302,..however, when I upgraded to 4.14.14-300 kernel the laptop will not boot when docked and using 2 external displays. It just freezes showing 3 side by side squares. If undocked, it will boot with no issues.

If I power off, and boot, but select the prior kernel 4.13.16-302 I can boot docked with 2 external displays. So my point being, can you try and boot to a prior kernel?

I'm off to open my issue. Good luck

NJ_Mahwah gravatar imageNJ_Mahwah ( 2018-02-08 09:01:03 -0500 )edit