Re: USB keyboard occasional key stuck

[Clinton Sprain <clintonsprain@gmail.com>]

I noticed your examples are both fn combos. I'm seeing something like
this and it seems specifically related to the fn key. Reproducible on a
Macbook (3,1) and a Lenovo Yoga 13. Sequence is simple:

Press key
Press fn
Release key
Release fn

The key will be 'stuck' until you press another key. It seems to only
apply to keys that are part of a fn combo, so affected keys vary from
one model to another; it appears that if nothing is mapped to fn+key on
a given hardware, the key is not affected. For example, delete is
affected on the Macbook (which has fn+delete = backspace), but not on
the Yoga (which has a dedicated backspace key). Arrow keys are an
exception to this rule though.

Is this what you're seeing?

- Clinton

On 02/17/2014 07:23 AM, Daniel J Blueman wrote:
> Across 5+ years of kernels, I've been seeing occasional (1-2 times per
> day) key-stuck issues where eg a fn+delete combo repeats delete until
> I press delete again. I've seen this happen with fn+ctrl+left, leaving
> left held and likewise with right.
>
> This has occurred on Apple laptops, external USB keyboards and Dell
> laptops, so seems like a linux USB input issue, as I haven't seen
> occur on Windows or MacOS on the same hardware.
>
> It seems a good move for me to rebuild and run a kernel with some USB
> HID instrumentation to locate this issue over time. Without apriori
> knowledge of the linux USB input stack, what is a good initial
> approach?
>
> Thanks,
>   Daniel