Switch Off Laptop Screen When Docked With Lid Close – CentOS 7

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Hi,

I’m using CentOS on a laptop that part of the time is connected to a docking station with two monitor connected to it. When the laptop lid is docked, its lid is closed, as the system is placed in a position where it’s not convenient to keep it open, let alone look at the screen.

Now in the past, with CentOS 5 (on a different laptop, but same physical config) and 6, the screen has automatically been switched off in this configuration – it’s been as if it was no longer there after I docked the machine, which is of course exactly what I want. After I recently switched to CentOS 7, however, I no longer get this behaviour. Even thought I can’t see the screen, it’s obvious that it’s on, or at least the system thinks so – it appears in display config, and  xrandr mentions it as “connected”.

Any idea what’s going on? Shouldn’t the screen just switch of automatically? What part of the system is supposed to handle this anyway? And what’s the best way around my problem? I’ve already disabled the screen in Display preferences, of course, but it seems like the situation should ideally be handled at a more global level, and also,
*my* display config obviously has no effect on the login manager. Which means I can’t really log in while the machine is locked, as the monitor is then still on, and guess where the login window appears…

Thanks,

– Toralf

2 thoughts on - Switch Off Laptop Screen When Docked With Lid Close – CentOS 7

  • Running CentOS 7/Gnome 3 and I also use two external monitors connected to my docking station. When laptop is docked (so lid is closed) internal display is turned off and only external displays are used. Same in gnome settings/displays : it shows my “Built-in display” as ‘lid closed’ and so only my external 24″ displays as enabled (as Primary and Secondary) (and I confirm that display is also off, and only gets back to enabled when I undock and open the lid)

  • Thanks. That’s useful information.

    Just wondering, what’s the normal sequence of operations when you connect? In my case it’s generally,

    1. Close the lid of the laptop (when carrying from somewhere else.0
    2. [ The laptop is suspended via the close action ]
    3. Connect to the dock
    4. Hit the power button so as to return from suspend.

    Anyhow, I think I’ve found what the issue is, at least in part: I
    actually switched to the LightDM display manager, on a somewhat experimental basis. I had GDM at first, but never actually docked the laptop before the chance. I didn’t really think about that when I posted the original message, and also thought the laptop lid etc. would be handled at a different level, but it would appear not. If I use GDM
    (which I’ve now tested once more), the display is disabled at the login screen, and this “translates” into the desktop, at least if its “local”
    monitor config is cleared. With LightDM, all 3 screens are active, the the setting is also carried through to the desktop.

    I’ve tested this with MATE as well as GNOME.

    This means I have a solution of sorts, but I’d really like to know why the LightDM has this problem, and the details of how these things work are still rather blurry…

    – Toralf

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