[ltp] T510i backlight

Jussi Larjo linux-thinkpad@linux-thinkpad.org
Wed, 01 Dec 2010 09:20:39 +0200

Replying to myself: I tried loading thinkpad_acpi with forced backlight 
control. /sys/class/backlight/thinkpad_screen tree appears and works 
with hotkeys but no actual brightness change this way either.

[31962.708349] thinkpad_acpi: ThinkPad ACPI Extras v0.24
[31962.708354] thinkpad_acpi: http://ibm-acpi.sf.net/
[31962.708356] thinkpad_acpi: ThinkPad BIOS 6MET61WW (1.24 ), EC 
[31962.708359] thinkpad_acpi: Lenovo ThinkPad T510, model 43149VG
[31962.709858] thinkpad_acpi: detected a 16-level brightness capable 
[31962.710211] thinkpad_acpi: radio switch found; radios are enabled
[31962.710230] thinkpad_acpi: This ThinkPad has standard ACPI backlight 
brightness control, supported by the ACPI video driver
[31962.710233] thinkpad_acpi: Disabling thinkpad-acpi brightness events 
by default...
[31962.720122] thinkpad_acpi: rfkill switch tpacpi_bluetooth_sw: radio 
is unblocked
[31962.725961] thinkpad_acpi: rfkill switch tpacpi_wwan_sw: radio is 
[31962.726445] Registered led device: tpacpi::thinklight
[31962.726545] Registered led device: tpacpi::power
[31962.726794] Registered led device: tpacpi::standby
[31962.726904] Registered led device: tpacpi::thinkvantage
[31962.732634] thinkpad_acpi: Backlight control force enabled, even if 
standard ACPI backlight interface is available
[31962.735613] thinkpad_acpi: Console audio control enabled, mode: 
monitor (read only)
[31962.741476] input: ThinkPad Extra Buttons as 

Please help?


On 30.11.2010 13:01, linux-thinkpad-request@linux-thinkpad.org wrote:
> Hello,
> I have a problem with the backlight of my T510i running Ubuntu 10.10,
> all other ACPI functions on this computer seem to work as usual. The
> brightness setting does not respond to hotkeys or power saving settings,
> neither manually echoing settings to
> /sys/class/backlight/acpi_video0/brightness. The brightness is normally
> at maximum, but sometimes very dim, only suspend/wakeup cycle will
> restore it to maximum.
> Echo and hotkey change the value in the sys file but have no real effect.