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ThinkPad T14 gen 2 screen dimming issue

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debian4236
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Joined: 2021-09-04 17:12

ThinkPad T14 gen 2 screen dimming issue

#1 Post by debian4236 »

So recently I bought a new laptop, and due to the shortages I had to get a ThinkPad T14 Gen 2 with a ryzen 7 processor which came with lenovo's privacy screen.

Overall Debian has been great, a lot less issues than other distributions, although the screen is stuck on maximum brightness and I can't seem to adjust it down. Moving the slider in software doesn't seem to have any effect (although the key macros do show the percentage going up and down, it's just the screen itself isn't getting dimmer or brighter).

I'm thinking it might be a driver issue related to that privacy screen? Although I'm a bit out of my element with this. Interestingly live-booting Kubuntu does work and I think they use similar software for screen dimming, although Kubuntu seems to be one iteration higher for xrandr server. Kubuntu has some other issues though which seem like they'll be harder to diagnose, so I'm trying to stick with Debian for now.

I was wondering if anyone has any ideas what might be the issue, or any troubleshooting I might be able to try? Or if it's possible to force-update xrandr?

Thanks

arzgi
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Re: ThinkPad T14 gen 2 screen dimming issue

#2 Post by arzgi »

I had also the white screen problem on my previous notebook, Samsun NC-10. It was a hw problem, but before I realized that I did bind the brightness key t o a xrandr script.

Try to check your power save settings also, how soon is the display dimmed.

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debian4236
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Re: ThinkPad T14 gen 2 screen dimming issue

#3 Post by debian4236 »

To clarify, the issue isn't that it's not dimming after a certain amount of time, the issue is that it's not dimming the screen. In software it thinks it is, shows the brightness changing animation for hotkeys, and lets me move the brightness slider in settings, however the actual screen is maintaining the same brightness.

Running xrandr gives me
xrandr: Failed to get size of gamma for output default
Screen 0: minimum 1920 x 1080, current 1920 x 1080, maximum 1920 x 1080
default connected 1920x1080+0+0 0mm x 0mm
1920x1080 77.00*

Interestingly when running xrandr --output Screen 0 --brightness .9 I get
xrandr: Failed to get size of gamma for output default
warning: output Screen not found; ignoring
xrandr: Need crtc to set gamma on.

So maybe whatever crtc is the solution? But the solutions I can find don't seem to apply to me

Marie SWE
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Re: ThinkPad T14 gen 2 screen dimming issue

#4 Post by Marie SWE »

Okay, just to check.. you have a T14 Gen2 and this is a new model released just a few month ago??? (I'm guessing now)
My guess is that maybe Debian stable doesn't support your drivers yet so you need to try out Debian testing...
I have some vague memory of ubuntu/kunbuntu is building on Testing if its not ubuntu LTS that builds stable..
Someone please correct me now. :D

and for lenovo's privacy screen is that angle view blurred.. is it a physical filter on screen or a software feature?
If it's a software feature.. then it's probably windows only... it came with OEM win10?
Why make things complicated in life, if you can make it easier for yourself... Do it. ;o)
You only have one life, so make the most of it and enjoy it while you can.

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debian4236
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Re: ThinkPad T14 gen 2 screen dimming issue

#5 Post by debian4236 »

Well I tried switching over to testing, and that didn't fix it, and then I tried reinstalling with the KDE desktop which froze before the lock screen trying to install some unavailable drivers (which I've previously installed by pulling a git repo and installing manually after I signed in). I switched to KDE Manjaro (a rolling release distro based on Arch) and that seems to have fixed my issues (although unfortunately it's not with Debian anymore).

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