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#1 2013-05-02 18:26:22

nunobaba
Member
From: paris, france
Registered: 2009-03-11
Posts: 16

[Solved] USB keyboard lagging problem: Where to start looking?

Hello everyone,

Here's the situation: I recently decided to try an upright work desk, quite a big change for someone to lean on his laptop, and adjusting to this new configuration, I decided to plug in a secondary keyboard (more details on specs at the end). The input device is detected accurately but behaves as if it was holding some keystrokes in its buffer. Two main inconveniences:

a) from the sequence of keystrokes "abcd", only "bcd" comes through, the keyboard eating up the first letter,
b) if quickly typed, the sequence "123456890" yields in something like "23567890", as some keystrokes at the beginning are eaten up.

The description of the situation might look a bit superficial, unorthodox but I would greatly appreciate if someone could point me out to the right direction where to look at. Is udev the troublesome component? Could there some issues between USB 2-type device plugged in USB 3-type slot?

The specs: a Dell XPS15 with the 3.7.10 kernel and a USB 101-touch Dell keyboard (with some mileage of 6+ years I guess).

Thanks for a lot.

Last edited by nunobaba (2013-05-03 09:24:32)

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#2 2013-05-02 19:41:31

brebs
Member
Registered: 2007-04-03
Posts: 3,412

Re: [Solved] USB keyboard lagging problem: Where to start looking?

Maybe USB auto-suspend - worth a try, anyway.

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#3 2013-05-03 09:09:59

nunobaba
Member
From: paris, france
Registered: 2009-03-11
Posts: 16

Re: [Solved] USB keyboard lagging problem: Where to start looking?

Thanks for the tip, brebs. The light at the end of the tunnel was to mess up with kernel module ehci_hcd. Removing it manually

rmmod ehci_hcd

and adding it again via

modprobe ehci_hcd

made the issue vanished.

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#4 2013-05-03 09:22:08

brebs
Member
Registered: 2007-04-03
Posts: 3,412

Re: [Solved] USB keyboard lagging problem: Where to start looking?

Sounds like a bug in the order of the kernel's USB module loading.

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#5 2013-05-03 09:29:21

nunobaba
Member
From: paris, france
Registered: 2009-03-11
Posts: 16

Re: [Solved] USB keyboard lagging problem: Where to start looking?

Are you suggesting to reconfigure the mkinitcpio and regenerate the initramfs?
Because mine is just the default with the default hooks base udev autodetect modconf block filesystems keyboard fsck

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#6 2013-05-03 09:33:07

brebs
Member
Registered: 2007-04-03
Posts: 3,412

Re: [Solved] USB keyboard lagging problem: Where to start looking?

No. I'm suggesting (vaguely) that this is a bug in the kernel, or at least in the precedence order of the kernel's USB drivers.

I suggest you use the kernel bugzilla, if you're interested in getting a proper fix.

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#7 2013-05-03 09:35:10

nunobaba
Member
From: paris, france
Registered: 2009-03-11
Posts: 16

Re: [Solved] USB keyboard lagging problem: Where to start looking?

Thanks for the tip; I'll check into this direction.

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#8 2014-07-28 19:11:18

VeeJ
Member
Registered: 2011-05-20
Posts: 11

Re: [Solved] USB keyboard lagging problem: Where to start looking?

Sorry if I answer to this thread after a year, but I'm experiencing the same issue right now with my wireless keyboard.

Removing the ehci_hcd module and readding it solves the issue for me too.

Any news about this?

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#9 2014-07-29 16:20:42

nunobaba
Member
From: paris, france
Registered: 2009-03-11
Posts: 16

Re: [Solved] USB keyboard lagging problem: Where to start looking?

Hey Veej, it really was a matter of latency caused by the usb module. How the mysterious issue was solved? I can't recall. I also switched to another PC since then. But you might have a grasp on it by looking into this direction.

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#10 2014-09-01 17:48:53

meteor
Member
Registered: 2014-09-01
Posts: 1

Re: [Solved] USB keyboard lagging problem: Where to start looking?

I have the same problem mention here
But I found out that it was caused by usb auto suspend ... (Which brebs mention..)

Laptop_mode forced every usb device into auto suspend mode....
figure out /usr/lib/udev/rules.d/99-laptop-mode.rules  solved my problem.

Edit: I found out that the correct way is to config /etc/laptop-mode/conf.d/usb-autosuspend.conf
Add USB keyboard to suspend black list should solve the problem.

Last edited by meteor (2014-09-02 07:33:06)

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