Laptop display shuts off when connecting external monitor

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Laptop display shuts off when connecting external monitor

Postby hellvetica » 2017-04-12 15:06

I have successfully installed Jessie with GNOME 3 desktop through a live boot USB drive. As far as i can tell everything works fine and i'm quite happy there's just one issue.

I have my HP notebook sitting on my desk connected to 2 external monitors through the VGA and HDMI ports and I still use the built in display so i can have 3 monitors for maximum productivity :)
This in and of it self works fine, but when i boot into Debian with the monitors connected, my built in monitor shuts off which is an issue because the login screen appears on it - so i can't log in.
If i boot with the monitors unplugged it works just fine, however once i log in and plug them in, the built in monitor shuts off again. I realized that the monitor brightness is at 0% so when i turned it up it worked fine but i can't do that on the login screen.
So every time an external monitor gets plugged in, the built in monitor brightness goes to 0.
This is just an inconvenience because i have to keep unplugging my monitors every time i boot the system.

Is there any way to change that?

Laptop - HP ProBook 450 G1
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Re: Laptop display shuts off when connecting external monito

Postby emariz » 2017-04-15 22:20

If the issue is indeed related to the screen brightness, one should be able to set it during the booting process, either by setting a kernel parameter or by specifying a brightness value through /etc/rc.local Please check this thread: viewtopic.php?f=5&t=78471

Also, laptops usually have a button (Fn+key) to send the output from its internal display to an external one. Could this button be related to your issue?

Have you tried deleting the monitors settings ~/.config/monitors.xml ?
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Re: Laptop display shuts off when connecting external monito

Postby pylkko » 2017-04-16 04:39

Some laptops have a hardware button that sets the modes when a display is added. So it might turn off the built in one, but after you press the button once (often fn plus another keyboard button) it then keeps them on. There may be more than two modes. Take a look to see if yours has one.
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