VGA connection failed - but why?

marcvangend · 2014-05-05 07:56:14

Last week, I experienced problems when connecting the VGA port on my Dell Latitude E5540 to a video projector (just when I was about to give a presentation, of course :-)).

This is what happened:
- I connected the projector's VGA cable to the VGA port. It was immediately recognized.
- In Gnome Control Center -> Displays, the projector showed up correctly as a second display device.
- The projector must have received some kind of signal, because its default no-signal screen was replaced with a black screen.
- Trying out different display settings (mirrored, secondary, primary), I couldn't get anything displayed on the projector.
- Laptop fn-keys and connecting the power adapter didn't help.
- Various commands/settings with xrandr didn't change anything.
- Reboot the laptop solved everything.

Obviously, I could not read the logs and investigate the cause of the failure that moment. However I would like to know what went wrong, and more importantly, if there's anything I can do to prevent this in the future.

Some more info on the display driver:

$ sudo lshw -c video
  *-display               
       description: VGA compatible controller
       product: Haswell-ULT Integrated Graphics Controller
       vendor: Intel Corporation
       physical id: 2
       bus info: pci@0000:00:02.0
       version: 09
       width: 64 bits
       clock: 33MHz
       capabilities: msi pm vga_controller bus_master cap_list rom
       configuration: driver=i915 latency=0
       resources: irq:62 memory:f6c00000-f6ffffff memory:e0000000-efffffff ioport:f000(size=64)

Please let me know if you need more info.

Inxsible · 2014-05-05 17:17:36

you updated a package, that required a reboot before it would recognize an external device. A package like the linux kernel maybe.

marcvangend · 2014-05-05 19:44:10

Thanks. Is that the only possible cause, or just a (highly) possible option? I don't recall updating the kernel without rebooting (like I usually do) that day... But otoh, my memory isn't perfect, you may very well be right.

Trilby · 2014-05-05 19:48:45

marcvangend wrote:

... anything I can do to prevent this in the future.

Try to replicate it. If you can't replicate the issue, then there is no need to worry about it happening in the future. If you can replicate it, you can gather logs and look for patterns.

There really isn't much point in speculating about an isolated incident: we could come up with dozens of hair-brained theories with no way to test any of them. Inxsible's is probably the only one that wouldn't be considered hair-brained.

Arch Linux

#1 2014-05-05 07:56:14

VGA connection failed - but why?

#2 2014-05-05 17:17:36

Re: VGA connection failed - but why?

#3 2014-05-05 19:44:10

Re: VGA connection failed - but why?

#4 2014-05-05 19:48:45

Re: VGA connection failed - but why?

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