Buttons controlling screen brightness do not work on Lenovo T470

piotrekg2 · 2017-11-03 19:16:01

Hi, I have just updated my system and the buttons controlling screen brightness have stopped working. When I run

# acpi_listen

and press combinations like Fn + F1-F9 I get no output. The script which handles the buttons resides in /etc/acpid/handlers/backlight and has never been changed:

#!/bin/sh                                                                       
bl_dev=/sys/class/backlight/intel_backlight                                     
                                                                                
min=0                                                                           
max=$(< $bl_dev/max_brightness)                                                 
step=25                                                                         
                                                                                
curr=$(< $bl_dev/brightness)                                                    
                                                                                
case $1 in                                                                      
  -) new=$(($curr - $step));;                                                   
  +) new=$(($curr + $step));;                                                   
esac                                                                            
                                                                                                                                  
new=$(($new < 0 ? 0 : $new))                                                    
new=$(($new > $max ? $max : $new))                                              
                                                                                
echo $new > $bl_dev/brightness

Any help would be appreciated.

piotrekg2 · 2017-11-11 10:50:19

Any ideas?

lo1 · 2017-11-11 11:34:57

Please don't bump your thread. What have you tried so far?
This could happen when there's a conflict between programs which use the same key bindings.
Post your pacman log (at least until that update).

piotrekg2 · 2017-11-12 20:47:11

@lo1: Here is the log you requested: https://pastebin.com/vthBGc05

As mentioned earlier, I've tried to run acpi_listen to see if button presses are intercepted at the lowest possible level. Combinations Fn + F10-12 are intercepted, Fn + F1-9 are not. If you have any idea what to check next, please let me know.

$ acpi_listen 
ibm/hotkey LEN0268:00 00000080 00001314 # F10
ibm/hotkey LEN0268:00 00000080 00001315 # F11
ibm/hotkey LEN0268:00 00000080 00001311 # F12

The update that has broken these buttons happened no later than 03-11-2017.

Last edited by piotrekg2 (2017-11-12 20:50:44)

lo1 · 2017-11-13 00:09:46

[2017-11-03 10:02] [ALPM] upgraded xkeyboard-config (2.21-2 -> 2.22-1)
[2017-11-03 19:28] [ALPM] removed xorg-xbacklight (1.2.1-1)
[2017-11-03 19:28] [ALPM] installed acpilight (1.0-2)

You have enough hints, let's get to work!
Tip: get rid of xorg-xbacklight configuration if any and reconfigure it according to acpilight

Lazarus555 · 2017-11-13 21:04:52

Try:

dmesg | grep thinkpad_acpi

if you see:

thinkpad_acpi: Disabling thinkpad-acpi brightness events by default...

well, that's why you don't see any events.

I'm using (more or less) the same notebook.

Do you have

xf86-video-intel

installed?

This is usually needed for so that Xorg can set the brightness for you (so your special config probably would not be needed).

You can try switching to "vendor" mode, where those key-pressed are handled internally, without any config needed (not tested by myself).
See here: https://bbs.archlinux.org/viewtopic.php?id=177616

Check also with:

showkey --scancodes

and see if the brightness button presses are "coming through".
If not, maybe you are already in "vendor" mode.

Hope this is not too confusing :-)
All the best,
Laz

cfr · 2017-11-14 01:14:00

Lazarus555 wrote:

Try:
dmesg | grep thinkpad_acpi
if you see:
thinkpad_acpi: Disabling thinkpad-acpi brightness events by default...
well, that's why you don't see any events.

This just isn't true. This message appears if the brightness is controlled by something else, too. I have this, but my brightness keys work just fine. It just means this particular module isn't handling them.

I'm using (more or less) the same notebook.
Do you have
xf86-video-intel
installed?
This is usually needed for so that Xorg can set the brightness for you (so your special config probably would not be needed).

On this particular hardware, you mean? Not for intel cards generally?

Lazarus555 · 2017-11-14 19:54:06

This just isn't true. This message appears if the brightness is controlled by something else, too. I have this, but my brightness keys work just fine. It just means this particular module isn't handling them.

Yes, you are right. And the way to make this module handle the events internally is (i think, but untested):

See here: https://bbs.archlinux.org/viewtopic.php?id=177616

On this particular hardware, you mean? Not for intel cards generally?

For Intel cards in general. Usually Xorg handles the keypresses (if not handled internally by the module) and in in order to access the backlight settings for a specific card, it needs the driver.

I personally set the brightness via a custom script via:

/sys/class/backlight/intel_backlight/brightness

Because the xf86-video-intel driver is (supposedly) in a bad state and being phased out eventually.

cfr · 2017-11-15 02:02:23

Lazarus555 wrote:

For Intel cards in general. Usually Xorg handles the keypresses (if not handled internally by the module) and in in order to access the backlight settings for a specific card, it needs the driver.
I personally set the brightness via a custom script via:
/sys/class/backlight/intel_backlight/brightness
Because the xf86-video-intel driver is (supposedly) in a bad state and being phased out eventually.

I don't have that driver installed and I did not need a custom script to get my brightness keys working. I would guess this is a bug for your particular intel graphics card - it certainly isn't true of all of them.

lo1 · 2017-11-15 11:32:22

Sorry to interrupt, but are you taking into account that the OP removed (unintentionally?) xorg-xbacklight and installed acpilight, claiming that the update that broke things was no later than 3-11?

EDIT: INTENTIONALLY, from OP's pacman.log:

[2017-11-03 19:27] [PACMAN] Running 'pacman -U acpilight-1.0-2-any.pkg.tar.xz'

@piotrekg2, didn't you think that was to mention before?

Last edited by lo1 (2017-11-15 15:06:57)

Lazarus555 · 2017-11-20 09:04:11

cfr wrote:

Lazarus555 wrote:
For Intel cards in general. Usually Xorg handles the keypresses (if not handled internally by the module) and in in order to access the backlight settings for a specific card, it needs the driver.
I personally set the brightness via a custom script via:
/sys/class/backlight/intel_backlight/brightness
Because the xf86-video-intel driver is (supposedly) in a bad state and being phased out eventually.
I don't have that driver installed and I did not need a custom script to get my brightness keys working. I would guess this is a bug for your particular intel graphics card - it certainly isn't true of all of them.

That might be true. Seems to be an issue with newer Lenovo notebooks.

https://wiki.archlinux.org/index.php/Le … ht_Control

I do not have a X1 Carbon, but a T470p.

cfr · 2017-11-20 17:10:34

Lazarus555 wrote:

That might be true. Seems to be an issue with newer Lenovo notebooks.

Not all new ones. I bought mine in September, so I certainly hope it is not consigned to the older hardware pile quite yet!

Arch Linux

#1 2017-11-03 19:16:01

Buttons controlling screen brightness do not work on Lenovo T470

#2 2017-11-11 10:50:19

Re: Buttons controlling screen brightness do not work on Lenovo T470

#3 2017-11-11 11:34:57

Re: Buttons controlling screen brightness do not work on Lenovo T470

#4 2017-11-12 20:47:11

Re: Buttons controlling screen brightness do not work on Lenovo T470

#5 2017-11-13 00:09:46

Re: Buttons controlling screen brightness do not work on Lenovo T470

#6 2017-11-13 21:04:52

Re: Buttons controlling screen brightness do not work on Lenovo T470

#7 2017-11-14 01:14:00

Re: Buttons controlling screen brightness do not work on Lenovo T470

#8 2017-11-14 19:54:06

Re: Buttons controlling screen brightness do not work on Lenovo T470

#9 2017-11-15 02:02:23

Re: Buttons controlling screen brightness do not work on Lenovo T470

#10 2017-11-15 11:32:22

Re: Buttons controlling screen brightness do not work on Lenovo T470

#11 2017-11-20 09:04:11

Re: Buttons controlling screen brightness do not work on Lenovo T470

#12 2017-11-20 17:10:34

Re: Buttons controlling screen brightness do not work on Lenovo T470

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