Re: USB keyboard occasional key stuck

On 18 February 2014 10:21, Peter Stuge [off-list ref] wrote:

Clinton Sprain wrote:

quoted

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

Fn is handled by the embedded controller (H8 as per Intel reference
design in case of Macbook or Thinkpad) which has its own closed
firmware which is rarely perfectly bug-free.

The likelyhood that the root-cause was in an embedded controller was
holding me back from reporting it.

I believe the Mac keyboards use the generic HID driver in Windows, so
it may be that there isn't a device-specific workaround, but maybe a
generic workaround, though I can't reason the mechanism without more
input-stack-fu.

I guess one test hack to confirm our sanity would be to re-read the
key state every 100ms until a matching key-up is received, logging
when it detects a disparity between key state and no key-up
received...?
-- 
Daniel J Blueman