Screen Brightness issues

Acuros · 2011-12-23 09:34:54

Hey there! just set up my first arch laptop, and am loving it!! (ubuntu user before)

I have set up mostly everything for power savings and i am getting okay battery life. The only thing that i cannot fix is setting my backlight brightness. it is permanently on 100%.
I have been trying for a few days now reading forums etc and cant seem to get it working. My current setup is:

Acer 1830T-3425

Intel core i3 330UM processor (first gen)
4gb ddr3 ram
64gb SSD
11.6" Led screen
**Intel HD Graphics** (with xf86-video-intel-2.17.0-2 installed)
Wireless B/G/N
Archlinux x86

i cannot control my brightness settings. Once i have this running im sure my battery will last alot longer

ive tried:

setpci -s 00:02.0 F4.B=50

xbacklight gives:
No outputs have backlight property

lspci gives
00:02.0 VGA compatible controller: Intel Corporation Core Processor Integrated Graphics Controller (rev 02)

any ideas? would be much appreciated!

Thanks

bohoomil · 2011-12-23 09:42:47

I use laptop-mode-tools to automatically set brightness level right after booting the system and it works exactly as it should.

Acuros · 2011-12-23 10:16:23

i checked the settings for laptop-mode and these are what i have:

#
# Should laptop mode tools control LCD brightness?
#
CONTROL_BRIGHTNESS=1

#
# Commands to execute to set the brightness on your LCD
#
BATT_BRIGHTNESS_COMMAND="echo 60"
LM_AC_BRIGHTNESS_COMMAND="echo 100"
NOLM_AC_BRIGHTNESS_COMMAND="echo 72"
BRIGHTNESS_OUTPUT="/sys/class/backlight/acpi_video0/brightness"

(as i dont have a cat /proc/acpi/video/VID/LCD/brightness location)

also
ENABLE_LAPTOP_MODE_TOOLS=1
ENABLE_LAPTOP_MODE_ON_BATTERY=1

still no change in backlight.

hongy19 · 2011-12-23 13:52:51

what do you have in /sys/class/backlight?

Acuros · 2011-12-23 15:50:59

Inside is a folder called acpi_video0
and inside that is

Acuros · 2011-12-24 07:25:07

i also forgot to add that i am running Openbox, if that helps.

skunktrader · 2011-12-24 07:32:53

On my machine the value of max_brightness is 15. Check to see if the values you are attempting to use (60, 72 and 100) are within the allowed range.

bohoomil · 2011-12-24 07:44:24

Try doing what skunktrader suggests. For example, set the settings as follows:

BATT_BRIGHTNESS_COMMAND="echo 12"
LM_AC_BRIGHTNESS_COMMAND="echo 14"
NOLM_AC_BRIGHTNESS_COMMAND="echo 14"

Acuros · 2011-12-25 08:58:26

I set those to exactly that, 12 14 14 and still no difference. it seems its not responding to anything i throw at it. so very weird... any other ideas ??

i appreciate all the help by the way, and happy holidays!

Shark · 2011-12-25 12:09:04

Type rc.d list. Is laptop-mode running? If not, issue "rc.d start laptop-mode".

Last edited by Shark (2011-12-25 12:09:39)

Acuros · 2011-12-26 07:19:42

Hey so i checked rc.d list
and it appears to be running.

bohoomil · 2011-12-26 07:56:57

Do you have the proper kernel driver loaded to support your LCD? If you had no problems running Ubuntu, you may do the following: boot Ubuntu LiveCD, and if you can control screen brightness there, run

lsmod > ubu-mods.txt

and compare with the output you get in Arch.

You can also enable DEBUG mode in lcd-brightness.conf and see if it helps track down the culprit.

mhertz · 2011-12-26 16:15:56

First, check /sys/class/backlight/acpi_video0/max_brightness to see the higest value; mine is 9, on an acer 5733... Then it goes from zero to the value in previously mentioned file.

Second, does your function keys work? If yes, then check if /sys/class/backlight/acpi_video0/brightness changes upon each key-press...

For my acer 5733, then the function keys dosen't work by default, and a workaround is needed ie. adding acpi_osi=Linux to your grub kernel bootline...

Still, I also have problems, since even though the file /sys/class/backlight/acpi_video0/brightness correctly changes with laptop-mode-tools, then the screen dosen't respond at bootup and just uses highest brightess anyways, and it's first when I press the function-key once for changing brightness, that the brightness actually notices the file /sys/class/backlight/acpi_video0/brightness, and changes brightness accordingly(+1 for the actual key-press made of the brightness function-key...)

Also, echoing a value into /sys/class/backlight/acpi_video0/brightness as root, also dosen't work...

Maybe you have the same issue, but unfortunetly, I haven't found a fix/workaround yet...

Last edited by mhertz (2011-12-26 17:33:46)

urza9814 · 2011-12-27 19:55:15

I'm a bit new to this stuff, so there may be some reason others haven't already suggested this, but have you tried adding 'acpi_osi=Linux' or 'backlight=vendor' to your grub kernel boot line? I had a similar issue with my backlight not being adjusted properly -- the first command was a suggestion I found everywhere, the second is what actually solved my problem -- though I had three folders in /sys/class/backlight, and the problem was just that my system was using the wrong one...

Also, have you tried echoing a value to /sys/class/backlight/acpi_video0/brightness, just to see if that'll actually do anything? For example:

echo 1 > /sys/class/backlight/acpi_video0/brightness

I would expect that wouldn't do a damn thing, otherwise xbrightness should probably be working, but it might be worth a shot...

mhertz · 2011-12-28 15:37:33

urza9814 wrote:

I'm a bit new to this stuff, so there may be some reason others haven't already suggested this, but have you tried adding 'acpi_osi=Linux' or 'backlight=vendor' to your grub kernel boot line?

Well, I had suggested acpi_osi=Linux in the post just before yours... Anyway, on my acer 5733, then acpi_osi=Linux makes the function keys work for brightness, but if adding backlight=vendor additionally, then it will not work, but that's just my system...

[...] -- though I had three folders in /sys/class/backlight, and the problem was just that my system was using the wrong one...

Thank you so much for that comment, mate! I was going crazy about not getting any brightness changes when echoing to /sys/class/backlight/acpi_video0/brightness, and only the function keys worked.

The function keys also would make the system update previously mentioned file, but when manually echoing to it, then nothing!

I wanted laptop-mode-tools to adjust brightness automatically upon bootup by echoing to that file, but because of the above, then I couldn't, but now i've found out that it's actually /sys/class/backlight/intel_backlight/brightness, that's the file which responds to echoing to! (In contrary to available documentation which all states the acpi_video0 folder's brightness file!)

To the OP, if you have the same issue as me(we both have acer's with nearly same specs), then lowest value is 95 and highest 976, and the file to echo to is: "/sys/class/backlight/intel_backlight/brightness"

I have this in lcd-brightness.conf from laptop-mode-tools:

BATT_BRIGHTNESS_COMMAND="echo 95"
LM_AC_BRIGHTNESS_COMMAND="echo 976"
NOLM_AC_BRIGHTNESS_COMMAND="echo 976"
BRIGHTNESS_OUTPUT="/sys/class/backlight/intel_backlight/brightness"

Last edited by mhertz (2011-12-28 15:41:08)

Acuros · 2011-12-30 08:21:06

hmm i do not have the intel_backlight that you are saying. only the acpi_video0

benob · 2011-12-30 19:19:11

Do you use the i915 module (for framebuffer)?

mhertz · 2011-12-31 01:23:41

Acuros wrote:

hmm i do not have the intel_backlight that you are saying. only the acpi_video0

OK...

What about the rest of what i've suggested to you?

Again, check maxbrightness so we know the max value.

Check if the function keys for brightness works; if not, then add acpi_osi=Linux to bootline in grub(/boot/grub/menu.lst, just after 'ro'...).

Then check if the number in the brightness file changes upon each press of the brightness-function-keys(fn + left/right)...

Finally, not related, but these bootlines also gives some better battery on newer intel systems:

pcie_aspm=force i915.i915_enable_rc6=1 i915.i915_enable_fbc=1 i915.lvds_downclock=1

Acuros · 2012-01-03 07:23:51

hey all,
i still could not get the brightness up and down buttons to work. but i did find out that during the post screen i can use the buttons to turn down the brightness. I do have to restart every time to change it but that is ok,

thanks mhertz for the information on the newer intel systems. i am currently running at about 5:53 mins (almost 6 hours!) on battery with lowered down brightness, laptop-mode and your additional settings.

Last edited by Acuros (2012-01-03 07:24:49)

Arch Linux

#1 2011-12-23 09:34:54

Screen Brightness issues

#2 2011-12-23 09:42:47

Re: Screen Brightness issues

#3 2011-12-23 10:16:23

Re: Screen Brightness issues

#4 2011-12-23 13:52:51

Re: Screen Brightness issues

#5 2011-12-23 15:50:59

Re: Screen Brightness issues

#6 2011-12-24 07:25:07

Re: Screen Brightness issues

#7 2011-12-24 07:32:53

Re: Screen Brightness issues

#8 2011-12-24 07:44:24

Re: Screen Brightness issues

#9 2011-12-25 08:58:26

Re: Screen Brightness issues

#10 2011-12-25 12:09:04

Re: Screen Brightness issues

#11 2011-12-26 07:19:42

Re: Screen Brightness issues

#12 2011-12-26 07:56:57

Re: Screen Brightness issues

#13 2011-12-26 16:15:56

Re: Screen Brightness issues

#14 2011-12-27 19:55:15

Re: Screen Brightness issues

#15 2011-12-28 15:37:33

Re: Screen Brightness issues

#16 2011-12-30 08:21:06

Re: Screen Brightness issues

#17 2011-12-30 19:19:11

Re: Screen Brightness issues

#18 2011-12-31 01:23:41

Re: Screen Brightness issues

#19 2012-01-03 07:23:51

Re: Screen Brightness issues

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