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GNUser

Member

Registered: 2017-03-16

Posts: 570  

how to make Thinkpad's Thinklight brighter?

I'm trying to make the ThinkLight brighter on my T400 ThinkPad, as it currently can be toggled on and off (via Fn + PgUp) but is so faint as to be totally useless. "ThinkLight" is the LED above the screen that can be used to illuminate the keyboard at night.

It looks like this:

It would be nice to try editing the contents of /sys/class/leds/tpacpi:thinklight/brightness, except that this file does not exist on my system (it does exist on some systems according to this). In fact, even though acpid is running and thinkpad_acpi kernel module is loaded, I have no evidence that acpid can detect the thinklight (e.g., /sys/class/leds/tpacpi::thinklight directory does not exist even though other /sys/class/leds/tpacpi::foo directories do exist).

If I could make acpi detect the thinklight, perhaps /sys/class/leds/tpacpi:thinklight/brightness would appear, I could edit it, and find joy.

Does anyone know how to make acpid detect a component it seems to be ignoring (or how to make the Thinklight brighter through some other means)?

Last edited by GNUser (2018-03-17 14:54:30)

ralph.ronnquist

Administrator

From: Battery Point, Tasmania, AUS

Registered: 2016-11-30

Posts: 1,253  

Re: how to make Thinkpad's Thinklight brighter?

There might be some thinklight brightness control somewhere under  /sys/bus/platform/drivers/thinkpad_acpi/ ?

GNUser

Member

Registered: 2017-03-16

Posts: 570  

Re: how to make Thinkpad's Thinklight brighter?

Thanks, ralph.ronnquist. I hadn't looked in there. After reading your post I snooped around in that directory but didn't find anything related to the thinklight.

I did some more tests and realized that even while at the GRUB menu, I'm able to toggle the thinklight on and off and its intensity is identical to what is is while running Devuan ASCII, Debian Jessie, or Arch Linux. I think that pretty much rules out a system configuration or init issue.

Acpid and the kernel are probably completely unaware that the thinklight exists. I'm starting to think that the dim thinklight is due to either a BIOS bug (my laptop has Libreboot) or a bad LED.

Last edited by GNUser (2018-03-17 06:16:34)

golinux

Administrator

Registered: 2016-11-25

Posts: 3,318  

Re: how to make Thinkpad's Thinklight brighter?

Why not boot a live disk to eliminate Libreboot as the culprit?

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GNUser

Member

Registered: 2017-03-16

Posts: 570  

Re: how to make Thinkpad's Thinklight brighter?

Good thought, golinux. Unfortunately, on a Libreboot system it is impossible to bypass Libreboot AFAIK, since it is Libreboot itself that loads live disks and passes on basic hardware data to them. (I think the same is true even for stock BIOS, but don't quote me bc I'm over my head in such low-level stuff.)

Last edited by GNUser (2018-03-17 05:19:48)

golinux

Administrator

Registered: 2016-11-25

Posts: 3,318  

Re: how to make Thinkpad's Thinklight brighter?

But wouldn't hurt to try would it?

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GNUser

Member

Registered: 2017-03-16

Posts: 570  

Re: how to make Thinkpad's Thinklight brighter?

I only know how to load a live image via the libreboot menu. Nevertheless, I'll try it and will report back.

Last edited by GNUser (2018-03-17 05:50:12)

GNUser

Member

Registered: 2017-03-16

Posts: 570  

Re: how to make Thinkpad's Thinklight brighter?

I tried booting a Linux Mint live image from USB stick. Same thinklight intensity, same directories in /sys/class/leds/ (i.e., some tpacpi::foo directories in there, but no tpacpi::thinklight).

The problem must be a bad LED or Libreboot bug. Sorry for the noise.

Last edited by GNUser (2018-03-17 06:34:25)