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nobodyuknow

Member

Registered: 2017-09-10

Posts: 174  

[SOLVED] screwy power management

Every time I unplug my newish laptop and then plug it back it, the screen goes to 30% brightness. I must reset brightness to 100% via the Power Management application. Please note that the brightness does not go to 30% until it is plugged back in, the reverse of what I would expect.

My older laptop has never exhibited this behavior.

Maybe it's a coincidence, but some of the logs contain the message "Jan 10 11:14:47 name-of-the-system kernel: [ 1957.046406] rtw_8821ce 0000:03:00.0: firmware failed to leave lps state."

I'm beginning to think that the Realtek wireless driver has an obscure bug that causes the brightness reduction.

The above is seen on three Devuan systems: Cinnamon, MATE, and Xfce, so it is not related to the choice of desktop. All run on external SSDs.

Both laptops are HP, but the older one has Broadcom wireless and Intel processor, while the newish one has Realtek wireless and AMD processor.

P.S. The brightness problem is only a minor inconvenience, but I'm trying to eliminate the page or two of error/warning messages seen during boot on the newish laptop.

Last edited by nobodyuknow (2023-01-12 00:22:22)

Head_on_a_Stick

Member

From: London

Registered: 2019-03-24

Posts: 3,125  

Website

Re: [SOLVED] screwy power management

I used to get those Realtek messages from my RTL8852AE but they've gone now I'm using the firmware from 2022-12-14, the .deb for which is available from ceres. Just download and install the .deb though, don't add the repositories.

https://deb.debian.org/debian/pool/non- … -3_all.deb

My backlight has always behaved itself so I don't think the wireless card has anything to do with that.

Last edited by Head_on_a_Stick (2023-01-12 07:33:07)

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Brianna Ghey — Rest In Power

nobodyuknow

Member

Registered: 2017-09-10

Posts: 174  

Re: [SOLVED] screwy power management

I installed that deb, but now when I unplug the power, the screen immediately dims and does not return to the initial brightness when I plug it back in. Oh well, it's only an annoyance.

Head_on_a_Stick

Member

From: London

Registered: 2019-03-24

Posts: 3,125  

Website

Re: [SOLVED] screwy power management

Did the .deb remove the Realtek error messages?

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Brianna Ghey — Rest In Power

nobodyuknow

Member

Registered: 2017-09-10

Posts: 174  

Re: [SOLVED] screwy power management

@Head_on_a_Stick

Good news, bad news. The first message no longer appears, but now there are new related ones. There are many pages of the first one and about one page of the second one, though they appear all the time, not just when the power cord is removed and reattached. Oh well, restoring brightness to 100% is an easy fix.

/var/log/messages
Jan 27 12:21:48 toshiba128 kernel: [ 8594.996429] rtw_8821ce 0000:03:00.0: unhandled firmware c2h interrupt

/var/log/syslog
Jan 27 12:25:52 toshiba128 kernel: [ 8839.278618] ACPI: \_PR_.P007: Found 2 idle states