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#1 2016-04-19 21:12:15

cherbert
Member
Registered: 2014-01-05
Posts: 18

Keyboard backlight issue

After the kernel update to 4.5 the keyboard backlight on my Lenovo X250 presents the following issue.

When I don't type or touch the trackpad for a few seconds (maybe one minute), the screen brightness is decreased (and this is normal). When I "wake up" the laptop from this situation it happens that the keyboard backlight turns on even if it was off before "sleeping".
The same happens when the screen is locked and then I unlock it.

Additional info: I use MATE as desktop environment.

Has some of you experienced the same? Solutions?

Last edited by cherbert (2016-04-19 21:12:47)

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#2 2016-04-25 08:57:21

gb
Member
Registered: 2016-04-25
Posts: 1

Re: Keyboard backlight issue

Also using an X250 and I'm seeing the same behavior. The keyboard backlight comes on whenever I boot or wake up the laptop.

I've found that unplugging or plugging-in the AC adapter also causes it to come on.

Last edited by gb (2016-04-25 09:06:16)

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#3 2016-05-07 20:28:46

cherbert
Member
Registered: 2014-01-05
Posts: 18

Re: Keyboard backlight issue

An update: the situation hasn't changed after the update to the new kernel today...

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#4 2016-10-19 08:38:54

cherbert
Member
Registered: 2014-01-05
Posts: 18

Re: Keyboard backlight issue

Googleing around, I found that the issue might be related to some files in

/sys/devices/platform/thinkpad_acpi/leds/tpacpi::kbd_backlight/

namely,

'/sys/devices/platform/thinkpad_acpi/leds/tpacpi::kbd_backlight':
totale 0
drwxr-xr-x 3 root root    0 19 ott 10.29 .
drwxr-xr-x 7 root root    0 19 ott 10.29 ..
-rw-r--r-- 1 root root 4096 19 ott 10.16 brightness
lrwxrwxrwx 1 root root    0 19 ott 10.16 device -> ../../../thinkpad_acpi
-r--r--r-- 1 root root 4096 19 ott 10.16 max_brightness
drwxr-xr-x 2 root root    0 19 ott 10.29 power
lrwxrwxrwx 1 root root    0 19 ott 10.00 subsystem -> ../../../../../class/leds
-rw-r--r-- 1 root root 4096 19 ott 10.16 trigger
-rw-r--r-- 1 root root 4096 19 ott 10.16 uevent

'/sys/devices/platform/thinkpad_acpi/leds/tpacpi::kbd_backlight/power':
totale 0
drwxr-xr-x 2 root root    0 19 ott 10.29 .
drwxr-xr-x 3 root root    0 19 ott 10.29 ..
-rw-r--r-- 1 root root 4096 19 ott 10.33 async
-rw-r--r-- 1 root root 4096 19 ott 10.33 autosuspend_delay_ms
-rw-r--r-- 1 root root 4096 19 ott 10.33 control
-r--r--r-- 1 root root 4096 19 ott 10.33 runtime_active_kids
-r--r--r-- 1 root root 4096 19 ott 10.33 runtime_active_time
-r--r--r-- 1 root root 4096 19 ott 10.33 runtime_enabled
-r--r--r-- 1 root root 4096 19 ott 10.33 runtime_status
-r--r--r-- 1 root root 4096 19 ott 10.33 runtime_suspended_time
-r--r--r-- 1 root root 4096 19 ott 10.33 runtime_usage

Any idea about whether they could somehow be involved or what they mean?

Last edited by cherbert (2016-10-19 08:39:22)

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#5 2016-10-19 14:51:33

ewaller
Administrator
From: Pasadena, CA
Registered: 2009-07-13
Posts: 19,739

Re: Keyboard backlight issue

What are the contents of the "Files":
/sys/devices/platform/thinkpad_acpi/leds/tpacpi::kbd_backlight/brightness
and
/sys/devices/platform/thinkpad_acpi/leds/tpacpi::kbd_backlight/max_brightness
?


Nothing is too wonderful to be true, if it be consistent with the laws of nature -- Michael Faraday
Sometimes it is the people no one can imagine anything of who do the things no one can imagine. -- Alan Turing
---
How to Ask Questions the Smart Way

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#6 2016-10-23 17:09:30

cherbert
Member
Registered: 2014-01-05
Posts: 18

Re: Keyboard backlight issue

ewaller wrote:

What are the contents of the "Files":
/sys/devices/platform/thinkpad_acpi/leds/tpacpi::kbd_backlight/brightness
and
/sys/devices/platform/thinkpad_acpi/leds/tpacpi::kbd_backlight/max_brightness
?

For the first is just

1

and for the second

2

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#7 2016-10-24 04:30:05

ewaller
Administrator
From: Pasadena, CA
Registered: 2009-07-13
Posts: 19,739

Re: Keyboard backlight issue

Try sudo bash -c 'echo 2 > /sys/devices/platform/thinkpad_acpi/leds/tpacpi::kbd_backlight/brightness'


Nothing is too wonderful to be true, if it be consistent with the laws of nature -- Michael Faraday
Sometimes it is the people no one can imagine anything of who do the things no one can imagine. -- Alan Turing
---
How to Ask Questions the Smart Way

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#8 2016-10-24 07:21:56

cherbert
Member
Registered: 2014-01-05
Posts: 18

Re: Keyboard backlight issue

ewaller wrote:

Try sudo bash -c 'echo 2 > /sys/devices/platform/thinkpad_acpi/leds/tpacpi::kbd_backlight/brightness'

Thanks. I understood that such file actually contains the current value of the brightness level.. So, the command suggested does exactly what the binding Fn + Space does (from what I saw).

Last edited by cherbert (2016-10-24 07:22:28)

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#9 2016-12-02 07:27:14

callmeish
Member
Registered: 2016-12-02
Posts: 1

Re: Keyboard backlight issue

I'm in the same boat (Mate, Thinkpad X250) and I think I've found a solution.

gsettings set org.mate.power-manager kbd-brightness-on-ac 0

That, at least on my machine, made it so that plugging/unplugging the laptop didn't change the keyboard backlight brightness I had set with Fn+Space.

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