Keyboard frozen after changing screen brightness

From	Jan Niggemann <jn@hz6.de>
Newsgroups	linux.debian.user
Subject	Keyboard frozen after changing screen brightness
Date	2016-03-30 12:20 +0200
Message-ID	<riloe-3NH-21@gated-at.bofh.it> (permalink)
Organization	linux.* mail to news gateway

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Hi all,

since upgrading Wheezy -> Jessie, I have areproducible issue. I'll try
my best to describe my setup, should anything be missing please ask for
clarification.

Environment
Lenovo T400
Jessie (i686)
GNOME 3.14.1

I boot normally and log in. When pressing Fn+Home to increase brightness
or Fn+End to decrease brightness, I observe a very sluggish behaviour of
the on screen brightness display (i.e. the "indicator icon" with the bar
beneath, not the brightness itself which changes instantly): It takes
almost one second before the icon comes up and the change in brightness
is reflected on the osd.
Secondly, when repeating keypresses to change to brightness, the
indicator kind of "locks up", flickers (not the whole monitor, only the
brightness indicator) and then the following message comes up:
"Could not grab your keyboard. A malicious client may be evesdropping on
your session or [...]".

After this, my keyboard is "gone" in X, i.e. no single keypress has any
effect in any X application. The mouse functions normally, as do
applications. Changing to a virtual console via Ctrl-Alt-F1 works, and
the keyboard is functioning normally there.

Nothing strange in Xorg.0.log or Xorg.0.log.old.
I think brightness is managed through standard ACPI control:
thinkpad_acpi: detected a 16-level brightness capable ThinkPad
thinkpad_acpi: This ThinkPad has standard ACPI backlight brightness
control, supported by the ACPI video driver
thinkpad_acpi: Disabling thinkpad-acpi brightness events by default...
thinkpad_acpi: Standard ACPI backlight interface available, not loading
native one

Any ideas why the indicator may show this sluggish behaviour (which I
expect to be the reason for the keyboard malfunction)?

jan

-- 
gpg --keyserver pgp.mit.edu --recv-keys 0x514FCA9C
F013 93C0 306C 1E31 4E00  09FA 21EC A2F6 514F CA9C

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Thread

Keyboard frozen after changing screen brightness Jan Niggemann <jn@hz6.de> - 2016-03-30 12:20 +0200
  Re: Keyboard frozen after changing screen brightness Sven Arvidsson <sa@whiz.se> - 2016-03-31 21:40 +0200
  Re: Keyboard frozen after changing screen brightness Celejar <celejar@gmail.com> - 2016-04-01 06:30 +0200

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