Xorg randomly can't find HDMI/DisplayPort monitor

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Xorg randomly can't find HDMI/DisplayPort monitor

Postby c5mage » 2017-04-21 12:47

Hi everyone,
This problem is very intermittent/episodic, but when it happens, it can last for days before (seemingly) fixing itself. Basically, I wake my Thinkpad T420s (with Debian Jesse) and on random occasions, it won't detect the external monitor which is my main display. It's connected to the thinkpad's DP port via a HDMI-DP adapter. I've seen other posts on forums about xrandr not detecting external monitors on wake, but those solutions have never worked for me in the ~6 months I've been dealing with this (since I got this laptop). Other things which have not worked: re-plugging in monitor during sleep, then waking; rebooting; xrandr --auto.

Here's a few lines from Xorg.1.log that might start to explain things:
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[  3888.623] (II) No input driver specified, ignoring this device.
[  3888.623] (II) This device may have been added with another device file.
[  3888.623] (II) config/udev: Adding input device HDA Intel PCH HDMI/DP,pcm=3 (/dev/input/event12)
[  3888.623] (II) No input driver specified, ignoring this device.
[  3888.623] (II) This device may have been added with another device file.
[  3888.623] (II) config/udev: Adding input device HDA Intel PCH HDMI/DP,pcm=7 (/dev/input/event13)
[  3888.623] (II) No input driver specified, ignoring this device.
[  3888.623] (II) This device may have been added with another device file.
[  3888.623] (II) config/udev: Adding input device HDA Intel PCH HDMI/DP,pcm=8 (/dev/input/event14)
[  3888.623] (II) No input driver specified, ignoring this device.


And xrandr output:
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Screen 0: minimum 320 x 200, current 1366 x 768, maximum 8192 x 8192
LVDS1 connected primary 1366x768+0+0 (normal left inverted right x axis y axis) 309mm x 173mm
   1366x768      60.00*+  39.98 
   1360x768      59.80    59.96 
   1024x768      60.00 
   800x600       60.32    56.25 
   640x480       59.94 
VGA1 disconnected (normal left inverted right x axis y axis)
HDMI1 disconnected (normal left inverted right x axis y axis)
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)


Any ideas? My setup has worked out-of-the-box just fine 99.9% of the time. And when this problem happens, it usually resolves randomly on a reboot or wake after anywhere from a few hours to a few days.
c5mage
 
Posts: 3
Joined: 2017-04-21 12:30

Re: Xorg randomly can't find HDMI/DisplayPort monitor

Postby debiman » 2017-04-21 17:02

enter
Code: Select all
dmesg -w
and then plug in the monitor.
it would be best if you could do this when it DOESN'T get recognized.
User avatar
debiman
 
Posts: 1013
Joined: 2013-03-12 07:18

Re: Xorg randomly can't find HDMI/DisplayPort monitor

Postby c5mage » 2017-04-21 20:34

Great, thank you. Although now (8 hours later) it just started working again...I'll see if I can recreate the problem.
c5mage
 
Posts: 3
Joined: 2017-04-21 12:30

Re: Xorg randomly can't find HDMI/DisplayPort monitor

Postby c5mage » 2017-04-23 13:45

Per usual, monitor is working consistently fine since recovering from the glitch the other day. Plugging in the monitor while running
Code: Select all
dmesg -w
doesn't register anything in the terminal. X also does not automatically switch to dual-monitor view, but running xrandr in another terminal prompts x to recognize the 2nd monitor per system settings.

Does that say anything? Will I just have to wait til next time it goes out to do more diagnostics?
c5mage
 
Posts: 3
Joined: 2017-04-21 12:30


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