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#1 2018-04-09 04:27:55

Deyyvon
Member
Registered: 2017-10-02
Posts: 10

Laptop's Built-In Keys Sporadically Cease to Function

Starting a month or two ago, I started noticing that certain keys on my built-in laptop keyboard (specifically the Ctrl, Enter, Spacebar, and Del keys) would, at random times, cease to function. I updated the kernel (can't remember to what, but I know it was newer than 4.4) and that seemed to fix the problem-- until recently, when it started back up again. I am currently running Arch Linux x86_64 with LightDM and XFCE/i3 (different sessions) on a Lenovo Flex 3-1580 with kernel version 4.15.15-1.

Things I Have Tried:

  • Restarting.

  • I thought the keyboard might be going out, so I tried using a bootable Kali. The keyboard worked flawlessly when typing for several minutes.

  • Switching TTYs. Turns out, the problem is not just in X, but also the console.

  • Checking the systemd journal. No errors or even anything relating to the keyboard.

  • Checking resource usage using htop. Nothing huge is running when the keys stop responding nor can I find any culpable processes.

  • Downgrading the kernel. I used a version prior to when the problem started (4.14). The problem persisted

NOTE: A while ago, I had to blacklist the input_polldev kernel module because it would send NULL (^@) characters to stdin every 800ms. Not sure if this would be relevant to this particular problem, but included just in case.

I have no idea how else to troubleshoot this. I'm confident that the issue is software-related because when the keyboard works, it works flawlessly. Also, this happens when I try to login using LightDM so I know it's not XFCE or i3. Any insights would be greatly appreciated.

Last edited by Deyyvon (2018-04-09 04:45:20)

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#2 2018-04-09 14:18:58

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

Re: Laptop's Built-In Keys Sporadically Cease to Function

Does this happen at the console?

I assume you are running under Xorg and not Wayland based upon your stated WMs.  Does xev   (package xorg-xev) see the keys? Does it report the correct scan codes?


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
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#3 2018-04-09 22:53:26

Deyyvon
Member
Registered: 2017-10-02
Posts: 10

Re: Laptop's Built-In Keys Sporadically Cease to Function

Yes, when I tried it, the console wouldn't recognize those keys either.

The next time it happens, I will try xev and see if it recognizes the codes and update this post.

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#4 2018-04-10 04:06:40

Deyyvon
Member
Registered: 2017-10-02
Posts: 10

Re: Laptop's Built-In Keys Sporadically Cease to Function

I just tried using xev to test the spacebar (since it stopped registering briefly) and it did not return any code. I also tried this with other keys that didn't work with the same result.

Last edited by Deyyvon (2018-04-10 04:38:33)

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#5 2018-04-10 14:21:26

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

Re: Laptop's Built-In Keys Sporadically Cease to Function

Well, this is going pear-shaped in a hurry.   From the console, does showkeys detect those keys?  (Note: showkeys will not work inside of an X-session or in a ssh shell; you must be at the console)


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 2018-04-11 16:48:44

Deyyvon
Member
Registered: 2017-10-02
Posts: 10

Re: Laptop's Built-In Keys Sporadically Cease to Function

showkey did not detect the non-functioning keys.

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#7 2018-04-11 17:21:25

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

Re: Laptop's Built-In Keys Sporadically Cease to Function

This is starting to sound like hardware.  What happens if you boot Windows, or an Arch install media?


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 2018-04-11 17:55:06

Deyyvon
Member
Registered: 2017-10-02
Posts: 10

Re: Laptop's Built-In Keys Sporadically Cease to Function

Per my second point, I thought it was hardware, so I booted a live Kali Linux USB. The keyboard worked flawlessly the entire time, which was greater than 15 minutes.

I did only try it once, and only with Kali. Should I try it with Windows or another live Linux distribution as well?

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#9 2018-04-25 17:45:35

Deyyvon
Member
Registered: 2017-10-02
Posts: 10

Re: Laptop's Built-In Keys Sporadically Cease to Function

I tried re-enabling input_polldev, but it had no effect. On the bright side, it doesn't send ^@ to stdout anymore.

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#10 2018-04-26 12:04:17

jvmcarneiro
Member
Registered: 2017-03-04
Posts: 12

Re: Laptop's Built-In Keys Sporadically Cease to Function

If possible, please do try using another OS for longer periods of time (much longer than 15min), specially an arch install media.

Do the keys come back after a while?
What do you do for them to come back?
Have you tried an external keyboard?

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#11 2018-06-27 20:05:03

Deyyvon
Member
Registered: 2017-10-02
Posts: 10

Re: Laptop's Built-In Keys Sporadically Cease to Function

Thank you @jvmcarneiro. Sorry for the late response.

What I've observed over the last two months is that the keyboard (in that time period) hasn't been unresponsive as it usually has been per se, but every once in a while one, two, or a few keys will not trigger. When that happens, I'll press down harder and it will usually trigger. Obviously, that seems like a hardware issue but the erratic and seemingly random nature of its past behavior makes me unsure.

Again, external keyboards work perfectly (which also makes me think this keyboard has wonky hardware), and the keys do come back after some time. The fact that the keyboard is working perfectly right now refutes the hardware theory, however...

I'll try a live Arch stick and see what that does if I notice a worsening of keyboard behavior.

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