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Old 13th February 2011, 09:31 AM
devent Offline
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Brightness control with intel drivers

Hello,
I have a new netbook, a Lenovo Z360 and everything except one thing works "out-of-the-box". The one thing is the brightness control. I think it's the same bug like in https://bugs.launchpad.net/ubuntu/+s...ux/+bug/538256

But I don't get anything in dmesg, it's just not working. setpci -s 00:02.0 F4.B=?? don't work, too. nomodeset acpi_backlight=vendor don't work, too.

I'm using Fedora 14 with KDE, 2.6.35.11-83.fc14.i686 and the intel drivers. Maybe somebody knows a workaround, usually brightness control works very well in the newer distributions. I had like 4 notebooks all with Fedora installed and brightness works, especially with the open source intel drivers I didn't expect any difficulties.
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  #2  
Old 13th February 2011, 11:23 AM
stevea Offline
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linuxfedorafirefox
Re: Brightness control with intel drivers

Does this (as root) print the brightness number ?

cat /sys/devices/virtual/backlight/acpi_video0/brightness

does "xbacklight" work ? (package of the same name).
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  #3  
Old 14th February 2011, 01:34 AM
devent Offline
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Re: Brightness control with intel drivers

xbacklight and cat /sys/devices/virtual/backlight/acpi_video0/brightness all works, but the brightness is still the same. The numbers are set and xbacklight is working but the display brightness stays the same.
dmesg don't return anything on brightness.

I don't know what's wrong. Maybe a bug in the kernel?

I moved my Fedora installation from an older notebook with a nvidia card (I used the nvidia drivers) to this notebook via hard disk transfer. I just removed the hard disk from the older and put it in the new one. Is there now a driver missing or something?

Everthing else is working, like wireless, sim card reader, sound, the Fn-keys, suspend, etc.
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Old 14th February 2011, 08:48 AM
johnscott Offline
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linuxfedorafirefox
Re: Brightness control with intel drivers

Assuming .. cat /sys/devices/virtual/backlight/acpi_video0/brightness returns 100 (ie brightness runs from 0 to 100)

Try as root .. echo "50" > /sys/devices/virtual/backlight/acpi_video0/brightness

If this works, you can write a small shell script with a slider dialogue called from a tray icon

Hope this helps
John

Last edited by johnscott; 14th February 2011 at 09:05 AM.
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Old 15th February 2011, 12:27 AM
stevea Offline
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linuxfedorafirefox
Re: Brightness control with intel drivers

Most Lenovo's /sys/devices/virtual/backlight/acpi_video0/brightness ary from 0 to 10 or 0 to 15.

echo 5 > /sys/devices/virtual/backlight/acpi_video0/brightness
or
xbacklight -set 50
xbacklight -set 75
xbacklight -set 100
(in percent).


The problem is likely that the ACPI brightness control is missing or different. Or (likely) that the kernel doesn't support this device yet.

Be sure the BIOS is up to date.
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  #6  
Old 15th February 2011, 03:00 AM
devent Offline
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linuxfedorafirefox
Re: Brightness control with intel drivers

If I use xbacklight the number is set in acpi_video0/brightness but nothing happens. The same for the Fn Keys, the number is set but the brightness of the display remains the same.

So I should update the BIOS? How can I test if the kernel is supporting the device or not? It's registered in the /sys tree.
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  #7  
Old 15th February 2011, 02:12 PM
stevea Offline
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Re: Brightness control with intel drivers

Do this (as root)
cat /proc/acpi/video/VID/LCD0/brightness

Then see if you can echo one of the 'level' values like
echo 13 > /proc/acpi/video/VID/LCD0/brightness


This may work where /sys/devices/... does not.
==

FYI
http://www.thinkwiki.org/wiki/Category:SL300
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  #8  
Old 16th February 2011, 03:19 PM
devent Offline
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linuxfedorafirefox
Re: Brightness control with intel drivers

I don't have /proc/acpi/video/VID/LCD0/brightness. I only have:
$ ls /proc/acpi/video/
GFX0
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Old 17th February 2011, 05:16 PM
bogatron Offline
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linuxfedorafirefox
Re: Brightness control with intel drivers

Quote:
Originally Posted by johnscott View Post
Assuming .. cat /sys/devices/virtual/backlight/acpi_video0/brightness returns 100 (ie brightness runs from 0 to 100)

Try as root .. echo "50" > /sys/devices/virtual/backlight/acpi_video0/brightness

If this works, you can write a small shell script with a slider dialogue called from a tray icon

Hope this helps
John
Try his code but for video1, the problem with my laptop is that the brightness app tries to change video0 instead of video1. I assume this is due to my hybrid video card which has little support at the moment - the app is trying to change the dormant card.

As root:
Code:
echo "10" > /sys/devices/virtual/backlight/acpi_video1/brightness
I should also add that the way I set mine now is using the keyboard buttons for brightness - the OSD shows up and a bar moves up and down but nothing happens until I close my laptop lid and open it again, then the brightness change takes effect. Not ideal but it will hold me over until 15 is released and *hopefully* addresses the issue.

Last edited by bogatron; 17th February 2011 at 05:21 PM. Reason: spacing, etc
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  #10  
Old 19th February 2011, 04:55 PM
devent Offline
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linuxfedorafirefox
Re: Brightness control with intel drivers

Thank you, but I don't have video1. I only have acpi_video0. It doesn't help to close the lid either. Good that the brightness is max otherwise I would have a bigger problem.
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  #11  
Old 1st May 2011, 07:45 PM
danieltofahrn Offline
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linuxchrome
Re: Brightness control with intel drivers

Devent,
Unfortunately, I have the same problem in Fedora 14. I also installed Fedora 15 Beta and 6.0 Debian and nothing changes..
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