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LonelyStar
Guru
Joined: 06 Dec 2005
Posts: 390
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 Posted: Tue Apr 01, 2008 10:38 am Post subject: How to use /sys/class/backlight? |
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Hi,
I have
| Code: | CONFIG_BACKLIGHT_LCD_SUPPORT=y
CONFIG_BACKLIGHT_CLASS_DEVICE=y |
in my .config (of my kernel).
/sys/class/backlight exists, but it is an empty directory ...
How do I use it or what do I have to do?
Thanks!
Nathan |
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timeBandit
Bodhisattva
Joined: 31 Dec 2004
Posts: 2719
Location: here, there or in transit
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| Posted: Tue Apr 01, 2008 1:38 pm Post subject: |
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| Kernel configuration help for CONFIG_BACKLIGHT_CLASS_DEVICE wrote: | This framework adds support for low-level control of the LCD backlight. This includes support for brightness and power.
To have support for your specific LCD panel you will have to select the proper drivers which depend on this option. |
Did you?
_________________
Plants are pithy, brooks tend to babble--I'm content to lie between them.
Super-short f.g.o checklist: Search first, strip comments, mark solved, help others. |
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LonelyStar
Guru
Joined: 06 Dec 2005
Posts: 390
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| Posted: Tue Apr 01, 2008 3:54 pm Post subject: |
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Hi,
No I did not 
There are only to drivers to choose from:
- Generic (aka Sharp Corgi) Backlight Driver
- Frontpath ProGear Backlight Driver
I included both as modules and loaded the modules ... nothing in /sys/class/backlight.
I have a thinkpad. Until 2.6.24 the thinkpad_acpi kernel module provided an backlight interface, but now I get a message in dmesg:
thinkpad_acpi: standard ACPI backlight interface available, not loading native one.
Where could I find the native one?
Thanks!
Nathan |
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m_gustafsson
Apprentice
Joined: 18 Mar 2007
Posts: 243
Location: Sweden
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| Posted: Mon Apr 07, 2008 9:40 pm Post subject: |
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Hi,
did you solve this one?
I also see problems on my Thinkpad X60s with loading the Thinkpad-acpi:
| Code: | dmesg | grep acpi
ACPI: LAPIC (acpi_id[0x00] lapic_id[0x00] enabled)
ACPI: LAPIC (acpi_id[0x01] lapic_id[0x01] enabled)
ACPI: LAPIC_NMI (acpi_id[0x00] high edge lint[0x1])
ACPI: LAPIC_NMI (acpi_id[0x01] high edge lint[0x1])
pnpacpi: exceeded the max number of mem resources: 12
thinkpad_acpi: ThinkPad ACPI Extras v0.17
thinkpad_acpi: http://ibm-acpi.sf.net/
thinkpad_acpi: ThinkPad BIOS 7BETC7WW (2.08 ), EC 7BHT37WW-1.10
thinkpad_acpi: Lenovo ThinkPad X60s
thinkpad_acpi: radio switch found; radios are disabled
thinkpad_acpi: standard ACPI backlight interface available, not loading native one... |
I also cannot load the acpi module from a terminal:
| Code: | # modprobe thinkpad_acpi
FATAL: Module thinkpad_acpi not found. |
On the other hand I have this in my directories:
| Code: | # ls /sys/class/backlight/
acpi_video0 acpi_video1 |
The kernel options which I have guessed matters are:
| Code: | # cat /usr/src/linux/.config | grep BACKLIGHT
CONFIG_BACKLIGHT_LCD_SUPPORT=y
CONFIG_BACKLIGHT_CLASS_DEVICE=y
CONFIG_BACKLIGHT_CORGI=y
CONFIG_BACKLIGHT_PROGEAR=y |
And:
| Code: | # cat /usr/src/linux/.config | grep THINKPAD
CONFIG_THINKPAD_ACPI=y
CONFIG_THINKPAD_ACPI_DEBUG=y
CONFIG_THINKPAD_ACPI_BAY=y |
Best regards, Mats |
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