OS/2, eCS & ArcaOS - Technical > Hardware

Turn off Laptop Display

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Neil Waldhauer:
I'd like to turn off the laptop display. Actually the screen saver ought to do it, but it doesn't.

Is there any way to turn off the display. Can it be turned on again later?

Test machine is a Lenovo Thinkpad T450s, in case it matters.

Dave Yeo:
On my T42, I have to use the function key to turn it off/on. Arca Noae's Snap claims it supports DPMS, while the stock ATI Snap correctly says it doesn't.
If the Screensaver doesn't turn it off, likely it is the same, no DPMS support. Likely it is supposed to use ACPI to control the screen, unluckily our ACPI doesn't support much in the way of things like turning off the screen unless the function keys are defined in the BIOS.
If the function keys don't work, likely you are out of luck. If really brave, you could try suspending the laptop, forget how now.
BTW, DPMS doesn't work at all in an UEFI boot.

Ibrahim Hakeem:
Hi Neil, I just wanted to chime in as a T450S user.

Aside from closing the laptop, there doesn't seem to be a way to turn off the screen.
Dave raises a good point - however, the function keys for screen controls don't even seem to register in the BIOS as they should. I split the blame between our limited ACPI support and negligence from Lenovo.

Interesting note to add: I recall asking about brightness controls for the T450S in a previous Warpstock event. Forgive me for not remembering who it was, but someone from ArcaNoae responded in IRC saying it might be possible, but upon looking at a few tables/resources then recanted by stating it isn't feasible without some serious work.

I personally reckon it wouldn't hurt for there to be at least some research undertaken for improved ACPI support, that way it could perhaps be outsourced to a passionate enough developer or maybe even BitWise. I can't imagine AN themselves would be taking up writing the necessary drivers anytime soon as it seems they've already got a lot on their plate with the current roadmap.

Neil Waldhauer:
The only hack I have figured out is that if I use an external monitor, then the internal screen is off. If I then turn off the external monitor, then the laptop is running with the screen off. I can also adjust the brightness of the external monitor.

This behavior started with the T60 and has continued through eight generations to the T450s. (at least eight -- I haven't tested some of the newer laptops)

Martin Iturbide:
Hi Dave

If I don't recall it wrong you modified Doodle Screen Saver to support DPMS with Panorama so it can turn off the display, right?. And I tested it sometime ago and it worked. Is it something related that can work to turn off the screens with Panorama?

I'm not sure if I got it right, within some  David Azarewicz presentation, he told that with the ACPI toolkit something can be developed to recognize some actions like presing the power button and closing the lid  and execute something.



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