LinuxQuestions.org - Power detection issue in slackware 14.2 (laptop connected and charging but screen is dim)

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Power detection issue in slackware 14.2 (laptop connected and charging but screen is dim)

below is the issue i face:

my adapter is plugged to my system, but still when i switch it on, i face a dimlit screen (brightness is very less)

i have to manually switch off and switch on my plug switch (and my monitor is lit up again properly to the right settings)

the laptop is being charged properly and i have tested with ON & OFF state and it is being detected correctly...the only issue is when i boot i get a low light and need to manually switch off and on my adapter switch to get a normal well lit display

Code:

cat /sys/class/power_supply/AC/online shows 0 (when unplugged) and 1 (when plugged)

Are you using XFCE? How did you install your system? Are you able to use software control or brightness keys?

i use fluxbox...

well i havent tried it with

Code:

Fn + brightness

keys as i have my laptop keyboard disabled on startup....only my usb keyboard works on startup which doesnt have the brightness keys to test the same...

i can control my brightness

Code:

inserting into /sys/class/backlight

but i am looking for auto-detection of adapter and resume brightness and vice-versa...

if i switch my laptop on, get the same brightness even if i unplug later (screen doesnt goes to dim state)

is power on/off not recognized or supported?

PFB some findings:

Code:

lspci | grep -i radeon

00:01.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Mullins [Radeon R4/R5 Graphics]



grep -i "\bconnected" /var/log/Xorg.0.log

[    59.667] (II) RADEON(0): Output eDP connected

here is my dmesg log which i think should be my issue related to brightness

Code:

~[3]#dmesg | grep -i brightness

[    0.359788] [Firmware Bug]: ACPI: No _BQC method, cannot determine initial brightness

[    0.360116] [Firmware Bug]: ACPI: No _BQC method, cannot determine initial brightness

[    8.845155] [Firmware Bug]: ACPI: No _BQC method, cannot determine initial brightness

[  13.461976] dell_laptop: Keyboard brightness level control not supported

nitecrawler,
Is this a new problem that started after some kind of software update or upgrade?

My first advice is to check your BIOS for screen brightness settings.
Also, in my experience, it's very unusual for a laptop's AC adapter to have a switch on it.
Are you using the manufacturer approved AC adapter?

Quote:

Originally Posted by STDOUBT (Post 5609249)

nitecrawler,
Is this a new problem that started after some kind of software update or upgrade?

well, i had upgraded to 14.2 recently, but not really sure if it was there before or popped up after the upgradation

Quote:

Originally Posted by STDOUBT (Post 5609249)

Also, in my experience, it's very unusual for a laptop's AC adapter to have a switch on it.
Are you using the manufacturer approved AC adapter?

yes, it is the manufacturer AC adapter...and no, there is no switch for the adapter, what i meant was the power source switch (the switch besides the socket i plug my adapter to)

very useful link (though outdated now as dsdt ships with the linux kernel now (correct me if i am wrong..thats the idea i got)

Code:

https://cannibalcandy.wordpress.com/2011/02/18/dsdt-editing-put-an-end-to-your-acpi-woes/

So are you going to go ahead and recompile your DSDT?
Another option might be to upgrade the BIOS on your laptop, assuming there is a "fixed" one available. It does look like you're dealing with a firmware bug.
It might also be advisable to reboot to another (older) kernel if you have one installed to see if the problem is some kind of regression in your currently-working kernel firmware.

well for a hackish note, i have just added this line to rc.local

Code:

echo 255 > /sys/class/backlight/radeon_bl0/brightness

and it gets me to max brightness everytime i boot....( use redshift so it doesnt burn my eyes and thats precisely why i need max brightness )

Quote:

Originally Posted by STDOUBT (Post 5609266)

So are you going to go ahead and recompile your DSDT?

i need to spend time reading through them before i try compiling...understand dsdt better and so on....

Quote:

Originally Posted by STDOUBT (Post 5609266)

Another option might be to upgrade the BIOS on your laptop, assuming there is a "fixed" one available. It does look like you're dealing with a firmware bug.

dont know how to do this either....unless i am sure a "fixed" bios is available (by googling more and more), i am not going to interfere with bios as of now....

Quote:

Originally Posted by STDOUBT (Post 5609266)

It might also be advisable to reboot to another (older) kernel if you have one installed to see if the problem is some kind of regression in your currently-working kernel firmware.

i do not have an older verison but a newer version yes....shall boot into it and check but for now i need to get some rest and come back later on this.....

Quote:

Originally Posted by nitecrawler (Post 5609273)

well for a hackish note, i have just added this line to rc.local

Code:

echo 255 > /sys/class/backlight/radeon_bl0/brightness

That will do for your machine. An example of more general solution:

Code:

cd /sys/class/backlight

 for i in $(ls); do

  if [ -e $i/max_brightness ]; then

    if [ -e $i/brightness ]; then

      cat $i/max_brightness > $i/brightness

    fi

  fi

 done

Hi,

I am curious as to if you have tried without the USB keyboard to see if the brightness stays to the preset value?

:hattip: