Brightness control help

horo · 2020-12-20 16:19:00

Hello there, I noticed that my function keys to dim my laptop screen don't actually work. They register a change, and the slide bar appears and moves but he screen brightness stays the same.
I've done some digging, installed xbacklight and followed the information here on passing kernel parameters to get things going.
Nothing has worked so far. I've removed the kerenal parameters, so I'm back to default.

Some relevent info:

horo@little:~$ lspci -knn | grep -iA2 'vga\|3d'
00:02.0 VGA compatible controller [0300]: Intel Corporation Mobile 945GSE Express Integrated Graphics Controller [8086:27ae] (rev 03)
	Subsystem: Toshiba America Info Systems Mobile 945GSE Express Integrated Graphics Controller [1179:ff60]
	Kernel driver in use: i915
horo@little:~$ find /sys/class/backlight
/sys/class/backlight
/sys/class/backlight/intel_backlight
/sys/class/backlight/acpi_video0
horo@little:~$ ls /sys/class/backlight/acpi_video0 /sys/class/backlight/intel_backlight
/sys/class/backlight/acpi_video0:
actual_brightness  device          subsystem
bl_power           max_brightness  type
brightness         power           uevent

/sys/class/backlight/intel_backlight:
actual_brightness  device          subsystem
bl_power           max_brightness  type
brightness         power           uevent
horo@little:~$

Changing kernel parameters usually ends up deleting 'acpi_video0'

xbacklight changes the intel_backlight brightness values, but the screen itself does not change

horo@little:~$ cat /sys/class/backlight/intel_backlight/brightness 
3784965
horo@little:~$ xbacklight -set 50
horo@little:~$ cat /sys/class/backlight/intel_backlight/brightness 
1892482
horo@little:~$

damo · 2020-12-20 17:08:46

Does this work? (Change the --output to suit your setup)

xrandr --output DVI-D-0 --brightness 2.5

Maybe try other values. If it works I have a script you can set to keybinds to increase/decrease brightness.

$ man xrandr
...
--brightness brightness
              Multiply  the gamma values on the crtc currently attached to the output to speci‐
              fied floating value. Useful for overly bright or overly  dim  outputs.   However,
              this  is  a  software only modification, if your hardware has support to actually
              change the brightness, you will probably prefer to use xbacklight.
...

horo · 2020-12-20 18:36:56

Thank you damo, but it appears xrandr doesn't like the DIV-D-0 for output. How would I find the proper output name or xid?

Edit: Found it!

horo@little:~$ xrandr -q
Screen 0: minimum 8 x 8, current 1024 x 600, maximum 32767 x 32767
LVDS1 connected primary 1024x600+0+0 (normal left inverted right x axis y axis) 220mm x 130mm
   1024x600      60.00*+
   1024x576      59.90    59.82  
   960x540       59.63    59.82  
   800x600       60.32    56.25  
   864x486       59.92    59.57  
   640x480       59.94  
   720x405       59.51    58.99  
   640x360       59.84    59.32  
   512x300       60.00  
VGA1 disconnected (normal left inverted right x axis y axis)
VIRTUAL1 disconnected (normal left inverted right x axis y axis)

LVDS1 was used in your command and had the effect of jacking up the gamma.
While this will be helpful it's not as nice as being able to lower the screens output brightness.
i tried this but to no effect, subbing in my identifier from running xrandr --verbose

Last edited by horo (2020-12-20 19:07:59)

brontosaurusrex · 2020-12-20 19:07:16

With some luck

xrandr --verbose | grep -i brightness | cut -f2 -d ' ' | tail -1

PackRat · 2020-12-20 19:25:20

What brand of laptop are you using?

My Toshiba has an internal toshiba-acpi that only works with Windows and conflicts with xbacklight and other linux tools.. I was able to go into the BIOS and disable it. You can check to see if your model has something similar.

horo · 2020-12-21 05:56:05

I'm using a Toshiba NB205-N210
Please tell me more of this interal acpi and BIOS disabling

PackRat · 2020-12-21 10:34:18

I need to correct myself, I didn't disable through the BIOS.

It's loaded as a kernel module so you can use lsmod to see if it's loaded.

lsmod | grep toshiba

If it's there you can blacklist the module. Reboot and xbacklight should be working. If it's not, you can try a different backlight control. I don't know what's in the Debian repos these days; xfce-power-manager and acpibacklight work on my Toshiba.

rbh · 2020-12-21 17:36:45

horo wrote:

I noticed that my function keys to dim my laptop screen don't actually work.

I can think of two reasons to dim the laptop screen

Conserve battery power
Facilitate reading in a dark room

In standard installation, xfce4-power-manager, is used to manage powersavings, included diming of screen on laptops. It is autostarted from /etc/xdg/autostart/xfce4-power-manager.desktop.
You can choose if you want to have an icon in tint2, for easy managment. Else, you can stant the ui from the menu => Preferences => Power managment.
If you temporarily want to dim the screen, just right click the icon and draw the meter to left.

When reading in dark room, there is applications to handle daily changes automaticley. I use redshift
I start it from ~/.config/bunsen/autostart replace "Lat:Long" with your coordinates:

redshift -l Lat:Long -t 5700:3600 -g 0.8 -m  randr -v &

rbh · 2020-12-21 18:03:03

horo wrote:

I'm using a Toshiba NB205-N210

Some of Toshibas netbooks in N200-series, was delivered with Ubuntu.
Do you know how it was with your pc?

What about Fn-keys for Volume, wifi, lock the comp etc; do they not work either?

ohnonot · 2020-12-21 19:51:44

Can you change the brightness at all?
E.g. by echoing a smaller/larger number to one of these files:

/sys/class/backlight/acpi_video0:
actual_brightness  device          subsystem
bl_power           max_brightness  type
brightness         power           uevent

(my guess would be actual_brightness)

horo · 2020-12-22 06:34:52

OK first-

horo@little:~$ lsmod |grep toshiba
toshiba_acpi           45056  0
industrialio           49152  1 toshiba_acpi
sparse_keymap          16384  1 toshiba_acpi
wmi                    20480  1 toshiba_acpi
toshiba_haps           16384  0
rfkill                 20480  4 toshiba_acpi,cfg80211
video                  40960  2 toshiba_acpi,i915

@rbh the Fn keyed brightness controls and slide bar do NOT effect brightness of the screen. I'm running vanilla Lithium here with xfce4-power-management starting at boot
Some of the other functions keys DO work, at least the ones I would commonly use, Volume control, numlock, wifi toggle.
There are a few that do not, such as touchpad toggle, and a few i don't recognize the symbols of.
edit: I should stress, the keys and slider function and register a change in the /sys/class/backlight/intel_backlight/actual_brightness, but this change does not produce any results on the screen's brightness level,

@ohnonot-
The values for /sys/class/backlight/intel_backlight/actual_brightness change when using the either the Fn Keys or the Slider, but the screen brightness does not actually change.

Weird thing, I cannot echo in a change to these files even as root

horo@little:~$ su
Password: 
root@little:/home/horo# echo 100 > /sys/class/backlight/intel_backlight/actual_brightness 
bash: /sys/class/backlight/intel_backlight/actual_brightness: Permission denied
root@little:/home/horo#

Last edited by horo (2020-12-22 06:44:21)

ohnonot · 2020-12-22 06:44:49

horo wrote:

Weird thing, I cannot echo in a change to these files even as root

horo@little:~$ su
Password: 
root@little:/home/horo# echo 100 > /sys/class/backlight/intel_backlight/actual_brightness 
bash: /sys/class/backlight/intel_backlight/actual_brightness: Permission denied
root@little:/home/horo#

Maybe it's another file somewhere under /sys.

@ohnonot-
The values for /sys/class/backlight/intel_backlight/actual_brightness change when using the either the Fn Keys or the Slider, but the screen brightness does not actually change.

Maybe the driver/GPU combo cannot handle this?
Have you ever been able to handle brightness on this laptop, under Linux or otherwise?
Maybe you need some magic ACPI kernel parameter.
This thread looks like it has some answers.

horo · 2020-12-22 07:28:22

This particular laptop is new to me and has only had this linux install on it.
Previously I had this same model and used BL Helium on it, and could swear that the brightness controls worked, but that was well over a year ago now.

I see in your linked thread that the person had a 20-intel.conf file in the X11 config stuff. I don't seem to have that, and it would make sense seeing as i have intel_backlight in my /sys

Edit: Progress!

I must have over looked something because I CAN set /sys/class/backlight/acpi_video0/brightness with echo as root and it DOES change my brightness level!
I CANNOT set /sys/class/backlight/intel_backlight/brightness with echo even though ls -l says root has write permission

Setting kernel parameters to acpi_backlight=vendor or acpi_backlight=native remove acpi_video0 from /sys but the brightness level persists after reboot.
I tried adding 20-intel.conf to my /usr/share/X11/xorg.conf.d/ using the same values from the link thread but that doesn't appear to change anything.
I tried to alter there file's BusID to something i saw from inxi -Gxx but that caused issues. On reboot it broke lightdm and I had to jump over to another tty and rm the file

So, acpi_video0 is controlling brightness, but I have to be in root to alter it. intel_backlight does nothing so far and all the methods I've tried (Fn keys, sliders, xbacklight) effect the intel_backlight brightness numbers

Last edited by horo (2020-12-22 08:56:02)

rbh · 2020-12-22 09:22:14

@rbh the Fn keyed brightness controls and slide bar do NOT effect brightness of the screen. I'm running vanilla Lithium here with xfce4-power-management starting at boot

Do you have an icon för powermanagment, in tint2? If not, start xfce4-power-management,from the menu, tick to show system icon.
Right-click the icon and change the level for brightness. Does that change the brightness for your screen?

Some of the other functions keys DO work, at least the ones I would commonly use, Volume control, numlock, wifi toggle.
There are a few that do not, such as touchpad toggle, and a few i don't recognize the symbols of.

All such information is available in your manual, which is good to glance through and study in some details.

edit: I should stress, the keys and slider function and register a change in the /sys/class/backlight/intel_backlight/actual_brightness, but this change does not produce any results on the screen's brightness level,

Ok, seems something is broken.

Weird thing, I cannot echo in a change to these files even as root

Not weird at all, as /sys/class/backlight/intel_backlight/actual_brightness is read only for root. File /sys/class/backlight/intel_backlight/brightness, is writable. Command

echo 100 >  /sys/class/backlight/intel_backlight/brightness

Does that change brightness off the screen?
That should be reflected in /sys/class/backlight/intel_backlight/actual_brightness.

Just for the sake of it, can you dim the screen when booting the BL live iso?
Can you use redshift?

Did you just found out that keys to alter screen-brightness did not work and wanted to fix it, or do you reale needed to dim your screen and found out you could not? If so, why do you need to dim the screen?
there might be another road to that goal...

PackRat · 2020-12-22 10:58:11

horo wrote:

OK first-

horo@little:~$ lsmod |grep toshiba
toshiba_acpi           45056  0
industrialio           49152  1 toshiba_acpi
sparse_keymap          16384  1 toshiba_acpi
wmi                    20480  1 toshiba_acpi
toshiba_haps           16384  0
rfkill                 20480  4 toshiba_acpi,cfg80211
video                  40960  2 toshiba_acpi,i915

Find out what toshiba_acpi does:

modinfo toshiba_acpi

On my Toshiba Satellite, I have to blacklist that module in order for the brightness keys to work. If you search Toshiba on the ArchWiki there are some entries for a couple of models. For the brightness keys to work on them, there are some xorg.conf and kernel parameters you can try.

horo · 2020-12-22 16:15:17

@PackRat

horo@little:~$ modinfo toshiba_acpi 
filename:       /lib/modules/4.19.0-12-686-pae/kernel/drivers/platform/x86/toshiba_acpi.ko
license:        GPL
description:    Toshiba Laptop ACPI Extras Driver
author:         John Belmonte
alias:          acpi*:TOS1900:*
alias:          acpi*:TOS6208:*
alias:          acpi*:TOS6207:*
alias:          acpi*:TOS6200:*
depends:        video,rfkill,industrialio,sparse-keymap,wmi
retpoline:      Y
intree:         Y
name:           toshiba_acpi
vermagic:       4.19.0-12-686-pae SMP mod_unload modversions 686 
sig_id:         PKCS#7
signer:         Debian Secure Boot CA
sig_key:        B5:5E:B3:B9
sig_hashalgo:   sha256
signature:      13:EF:33:0A:DF:35:B8:42:A0:0F:D6:72:FB:8D:E5:84:AE:D9:CC:23:
		A9:64:B7:DA:EC:1F:EF:8B:DF:11:6C:1D:F6:C3:0E:94:09:9E:E0:2A:
		06:58:AE:95:5F:B4:67:75:48:7D:7E:DC:F3:04:1C:89:E6:32:AF:C9:
		E0:65:93:AB:3B:EE:3E:7F:32:69:E6:B9:08:51:7E:E5:0E:F1:ED:99:
		E2:D8:07:98:1A:42:02:DB:F6:4B:54:5E:EA:CD:66:93:B5:B7:84:DA:
		2A:FC:AA:B0:3B:C8:1D:16:D7:63:6E:B4:0C:45:93:0C:6E:62:A1:D0:
		78:D4:15:C7:5B:F1:FF:B3:2F:47:A6:A4:36:29:87:B7:8E:06:3F:87:
		94:60:23:62:3E:83:0E:4E:A6:7C:50:3B:6A:71:48:85:31:AE:F3:D9:
		EC:BB:30:26:B4:55:B9:CC:B0:09:10:5A:40:F5:B5:6C:ED:4E:13:F5:
		40:F8:28:5F:5E:22:5C:DA:2B:FD:7D:B2:9E:99:3A:C1:69:1D:33:A5:
		D0:E8:BA:81:A6:EA:CD:D8:42:6F:AC:4D:72:B1:CA:3D:A5:E4:EE:2B:
		E0:8F:7E:F9:37:A1:62:F0:C9:58:E7:B6:66:D3:A8:B8:1C:BE:99:9D:
		F3:BB:D3:44:5B:5F:4C:E4:64:8F:17:50:74:61:C3:F4
parm:           disable_hotkeys:Disables the hotkeys activation (bool)

@rbh
I need the brightness control to stop bothering the Mrs. when linuxing in bed in the middle of the night. I posted an update where I found I could control brightness as root by manipulating apci_video0/brightness
From my understanding I can change permissions and and key bindings to enact a script that would let my Fn keys alter this file, but I would rather figure out why intel_backlight isn't doing what it should since ALL the applications that I have effect this value.

PackRat · 2020-12-22 17:38:36

Try blacklisting the module and see if your brightness and other keys work. In /etc/modprobe.d you should have a blacklist.conf file (create one if you don't) and add:

blacklist toshiba_acpi

Reboot and see if your brightness keys and everything is working. If xbacklight isn't working try it as "sudo xbacklight" - I've seen some posts about xbacklight needing root privileges.

If there are some side effects, you can delete the line.

Last edited by PackRat (2020-12-23 02:37:35)

ohnonot · 2020-12-22 20:15:44

rbh wrote:

Do you have an icon för powermanagment, in tint2? If not, start xfce4-power-management,from the menu, tick to show system icon.
Right-click the icon and change the level for brightness. Does that change the brightness for your screen?

Important question.

horo · 2020-12-22 23:52:25

ohnonot wrote:

rbh wrote:
Do you have an icon för powermanagment, in tint2? If not, start xfce4-power-management,from the menu, tick to show system icon.
Right-click the icon and change the level for brightness. Does that change the brightness for your screen?
Important question.

sorry, thought i made it clear that xfce4-power-management is running and activating the slider with right click changes the /intel_backlight/brightness numbers but does not effect the screen at all

ohnonot · 2020-12-23 08:33:50

OK. I thought you were refering to some hotkey popup.
So, since manually echoing values to a file works, the question is why doesn't xfce4-power-manager.
Next step: investigate how xfce4-power-manager works.
Options:
Read https://docs.xfce.org/xfce/xfce4-power-manager/
Remove it from BL/openbox autostart and start it manually in a terminal, and see if it complains when you try to move the slider.
Similarly, but with "journalctl -f"

rbh · 2020-12-23 10:05:36

ohnonot wrote:

So, since manually echoing values to a file works, the question is why doesn't xfce4-power-manager.

I do not think horo has said that works, neither if Fn keys works in BL live iso. If it wirks in live session, then next step I think would be to blacklist toshiba_acpi.

rbh · 2020-12-23 10:35:25

horo wrote:

I posted an update where I found I could control brightness as root by manipulating apci_video0/brightness

Something happened to that post, it can not be found.
So, you are not working in directory /sys/class/backlight/intel_backlight? what other files do you have there? Also an actual_brightness? They are not modified by pressing Fn-key?

From my understanding I can change permissions and and key bindings to enact a script that would let my Fn keys alter this file, but

You can do what you want on your machine, but is it wise to change file persission on system files? I think not...

I would rather figure out why intel_backlight isn't doing what it should since ALL the applications that I have effect this value.

You still have both "Toshiba Laptop ACPI Extras Driver" and intel_backlight? Maybe you should decide to use only one?

I still think it is a good idea for you to boot into live session and see it Fn-keys work there and if so investige difference between your install and live session.

Last edited by rbh (2020-12-23 10:35:53)

rbh · 2020-12-23 10:46:56

Use intel_backlight instead of acpi_backlight0?

rbh · 2020-12-23 10:53:44

Arch Wiki on Backlight
https://wiki.archlinux.org/index.php/Ba … ne_options

horo · 2020-12-24 17:32:03

Alright , I dug up the live USB used to install Lithium and here is what I learned-
1. The brightness set by echo X > /sys/class/backlight/acpi_video0/brightness persists even when booting to the live USB, so it's being saved somewhere on the motherboard
2. Live USB Lithium acts the same as installed Lithium. Fn keys register and manipulate the intel_backlight/brightness variable, but this does not effect the screen brightness, only acpi_video0/brightness does
3.Passing kernel parameters acpi_backlight=vendor or acpi_backlight=none remove the /sys/class/backlight/acpi_video0 directories on reboot, but the brightness level stays at what ever level it was set at previously.
Fn Keys, xfce4-power-manager slider, xbacklight all manipulate intel_backlight/brightness without effecting the screen.
4. i have confirmed by running inxi -G that I only have one graphics gpu, since several examples listed had multiple gpus that conflicted causing the problem

I have not blacklisted toshiba_acpi or made an xorg profile yet. I'll try the blacklisting when time permits, but ya know, holidays. I feel like I do not know enough for seting an xorg profile.

#1 2020-12-20 16:19:00

Brightness control help

#2 2020-12-20 17:08:46

Re: Brightness control help

#3 2020-12-20 18:36:56

Re: Brightness control help

#4 2020-12-20 19:07:16

Re: Brightness control help

#5 2020-12-20 19:25:20

Re: Brightness control help

#6 2020-12-21 05:56:05

Re: Brightness control help

#7 2020-12-21 10:34:18

Re: Brightness control help

#8 2020-12-21 17:36:45

Re: Brightness control help

#9 2020-12-21 18:03:03

Re: Brightness control help

#10 2020-12-21 19:51:44

Re: Brightness control help

#11 2020-12-22 06:34:52

Re: Brightness control help

#12 2020-12-22 06:44:49

Re: Brightness control help

#13 2020-12-22 07:28:22

Re: Brightness control help

#14 2020-12-22 09:22:14

Re: Brightness control help

#15 2020-12-22 10:58:11

Re: Brightness control help

#16 2020-12-22 16:15:17

Re: Brightness control help

#17 2020-12-22 17:38:36

Re: Brightness control help

#18 2020-12-22 20:15:44

Re: Brightness control help

#19 2020-12-22 23:52:25

Re: Brightness control help

#20 2020-12-23 08:33:50

Re: Brightness control help

#21 2020-12-23 10:05:36

Re: Brightness control help

#22 2020-12-23 10:35:25

Re: Brightness control help

#23 2020-12-23 10:46:56

Re: Brightness control help

#24 2020-12-23 10:53:44

Re: Brightness control help

#25 2020-12-24 17:32:03

Re: Brightness control help

Board footer