Arch Linux

_clark_

Member

Registered: 2008-05-06

Posts: 14

[SOLVED] Key releases are not detected

SOLVED : it was an hardware/child problem ;-)

The plastic bar of the multimedia keys had moved slightly. Despite an apparent upward movement, permanent or intermittent signals were sent, as if the keys were pressed.
Disassembly and reassembly of the keyboard solved the problem.
It seems one of my children played with the keyboard :-)

############

Hello,

I have a very strange behavior with the multimedia keys of my keyboard. Evdev doesn't detect the release of the keys, conducting to disturb the behavior of the DE : for instance, when I try to increase the audio volume, it grows itslef up to 100%. Or, when I want to play music, the music soft (Clementine) switch permanently between play and pause....

Here are some output from libinput :

# libinput debug-events
-event4   DEVICE_ADDED     Power Button                      seat0 default group1  cap:k
-event3   DEVICE_ADDED     Power Button                      seat0 default group2  cap:k
-event6   DEVICE_ADDED     HDA ATI HDMI HDMI/DP,pcm=3        seat0 default group3  cap:
-event7   DEVICE_ADDED     HDA ATI HDMI HDMI/DP,pcm=7        seat0 default group3  cap:
-event0   DEVICE_ADDED     HID 046a:0023                     seat0 default group4  cap:k
-event1   DEVICE_ADDED     HID 046a:0023                     seat0 default group4  cap:kp scroll-nat
-event2   DEVICE_ADDED     Logitech USB Laser Mouse          seat0 default group5  cap:p left scroll-nat scroll-button
-event9   DEVICE_ADDED     HDA Intel MID Rear Mic            seat0 default group3  cap:
-event10  DEVICE_ADDED     HDA Intel MID Line                seat0 default group3  cap:
-event11  DEVICE_ADDED     HDA Intel MID Line Out Front      seat0 default group3  cap:
-event12  DEVICE_ADDED     HDA Intel MID Line Out Surround   seat0 default group3  cap:
-event13  DEVICE_ADDED     HDA Intel MID Line Out CLFE       seat0 default group3  cap:
-event14  DEVICE_ADDED     HDA Intel MID Line Out Side       seat0 default group3  cap:
-event15  DEVICE_ADDED     HDA Intel MID Front Headphone     seat0 default group3  cap:
-event8   DEVICE_ADDED     HDA Intel MID Front Mic           seat0 default group3  cap:
-event0   KEYBOARD_KEY      +3.73s      *** (-1) pressed
 event0   KEYBOARD_KEY      +3.83s      *** (-1) released
 event0   KEYBOARD_KEY      +4.63s      *** (-1) pressed
 event0   KEYBOARD_KEY      +4.71s      *** (-1) released
 event0   KEYBOARD_KEY      +5.54s      *** (-1) pressed
 event0   KEYBOARD_KEY      +5.61s      *** (-1) released
 event0   KEYBOARD_KEY     +13.50s      *** (-1) pressed
 event0   KEYBOARD_KEY     +13.66s      *** (-1) pressed

The 6 first events of event0 (my system-keyboard) correspond to keys 'a' 'z' and 'e', and are normal : 'PRESSED' then 'RELEASED'.

But the lasts are for the 'Mute' key. As you can see, For one 'click' on this key, it's detected as pressed, and re-pressed, and so on...

Any help will be appreciated ;-)

Regards,

Clark

Last edited by _clark_ (2017-08-26 17:32:32)

olive

Member

From: Belgium

Registered: 2008-06-22

Posts: 1,490

Re: [SOLVED] Key releases are not detected

This is a common problem for some multimedia keys. There is a list of known affected laptops (it usually affect laptops) where the kernel generate a released events just after the key is pressed (a forced release event). The file is /usr/lib/udev/hwdb.d/60-keyboard.hwdb and it contains some explanation. Probably your laptop is not mentioned in this file while it should. Try to select a rule that contains the same problematic keys and add your laptop (more precisely your "multimedia keyboard" (media keys are seen as an additional keyboard) to the file (or as a quick and dirty solution add a generic char everywhere in the rule). Don't forget to run "systemd-hwdb update" after having modified the file (this file will be overwritten by each update of systemd, configure pacman accordingly or read the info about creating another file that won't be overwritten).

Last edited by olive (2017-08-25 21:18:01)

_clark_

Member

Registered: 2008-05-06

Posts: 14

Re: [SOLVED] Key releases are not detected

Hi,

Thank you for your answer. I had a look in this file, and I confess I'm a bit confused. Firstly, my computer is a desktop one, with a Cherry keyboard  I belong for years now, and that's never happened. Secondly, I've tried this :

#showkey --keycodes
kb mode was ?UNKNOWN?
[ if you are trying this under X, it might not work
since the X server is also reading /dev/console ]

press any key (program terminates 10s after last keypress)...
keycode  28 release
akeycode  16 press
keycode  16 release
ekeycode  18 press
keycode  18 release
keycode 165 release
keycode 115 press

The 2 last outputs are from my multimedia "+" key. As you can see, it's firstly detected as "released" then "pressed", so exactly the contrary of I did (and the contrary of the other keys). Don't you think it's a kernel problem ?

Last edited by _clark_ (2017-08-26 16:44:17)

_clark_

Member

Registered: 2008-05-06

Posts: 14

Re: [SOLVED] Key releases are not detected

update : it's not totally a kernel problem, but kernel seems to be partially implied. With linux-lts, I have :

# showkey --keycodes
kb mode was ?UNKNOWN?
[ if you are trying this under X, it might not work
since the X server is also reading /dev/console ]

press any key (program terminates 10s after last keypress)...
keycode  28 release
akeycode  16 press
keycode  16 release
zkeycode  17 press
keycode  17 release
keycode 115 press

The keycode 165 release isn't here yet, but keycode 115 release is not detected.

_clark_

Member

Registered: 2008-05-06

Posts: 14

Re: [SOLVED] Key releases are not detected

SOLVED : it was an hardware problem. See first post for assessment.