Bug 20862

Summary:	Brightness keys repeat after key is released
Product:	xorg	Reporter:	Sam Morris <sam>
Component:	Input/evdev	Assignee:	Peter Hutterer <peter.hutterer>
Status:	RESOLVED DUPLICATE	QA Contact:	Xorg Project Team <xorg-team>
Severity:	normal
Priority:	medium	CC:	richard
Version:	7.4 (2008.09)
Hardware:	x86-64 (AMD64)
OS:	Linux (All)
URL:	http://bugzilla.gnome.org/show_bug.cgi?id=576283
Whiteboard:
i915 platform:		i915 features:

Description Sam Morris 2009-03-25 09:14:52 UTC

I have a Samsung Q45 laptop. When I press Fn + UP/Down to change the laptop's brightness, there is one brightness key event, followed by a pause, and then further events repeat very rapidly.

If I disable key autorepeat (xset r off) then there are no brightness events at all!

Monitoring the events via 'lshal -m' reveal a single event, regardless of the xserver's autorepeat setting.

This is a problem because gnome-power-manager gets its brightness key events from the X server, and when I press a key to change the brightness, it grabs the keyboard and does not ungrab it until the brightness stops changing, which means I need to switch to a text mode console and log in and kill it in order to get control of the X server back...

This was originally reported at <http://bugzilla.gnome.org/show_bug.cgi?id=576283>. Further details and logs can be found there.

Comment 1 Julien Cristau 2009-03-25 09:34:37 UTC

> I have a Samsung Q45 laptop. When I press Fn + UP/Down to change the laptop's
> brightness, there is one brightness key event, followed by a pause, and then
> further events repeat very rapidly.
> 
> If I disable key autorepeat (xset r off) then there are no brightness events at
> all!
> 
> Monitoring the events via 'lshal -m' reveal a single event, regardless of the
> xserver's autorepeat setting.

Can you run evtest on the corresponding input device?  When you press
and release that key, you should see something like:
Event: time 1237998837.702709, type 1 (Key), code 224 (Brightness down),
value 1
Event: time 1237998837.702722, type 1 (Key), code 224 (Brightness down),
value 0
(your symptoms might be due to the kernel not sending a keyrelease
event)

Comment 2 Sam Morris 2009-03-25 10:55:52 UTC

Here's the output of evtest when pressing the 'Brightness up' key once:

Testing ... (interrupt to exit)
Event: time 1238003574.986627, type 4 (Misc), code 4 (ScanCode), value 88
Event: time 1238003574.986648, type 1 (Key), code 225 (Brightness up), value 2
Event: time 1238003574.986653, -------------- Report Sync ------------
^C

Compare this to the output when pressing, and holding, the 'A' key:

Testing ... (interrupt to exit)
Event: time 1238003651.359355, type 4 (Misc), code 4 (ScanCode), value 1e
Event: time 1238003651.359376, type 1 (Key), code 30 (A), value 1
Event: time 1238003651.359381, -------------- Report Sync ------------
Event: time 1238003651.610226, type 4 (Misc), code 4 (ScanCode), value 1e
Event: time 1238003651.610248, type 1 (Key), code 30 (A), value 2
Event: time 1238003651.610253, -------------- Report Sync ------------
Event: time 1238003651.640940, type 4 (Misc), code 4 (ScanCode), value 1e
Event: time 1238003651.640962, type 1 (Key), code 30 (A), value 2
Event: time 1238003651.640969, -------------- Report Sync ------------
Event: time 1238003651.671659, type 4 (Misc), code 4 (ScanCode), value 1e
Event: time 1238003651.671679, type 1 (Key), code 30 (A), value 2
Event: time 1238003651.825276, -------------- Report Sync ------------
Event: time 1238003651.881575, type 4 (Misc), code 4 (ScanCode), value 1e
Event: time 1238003651.881596, type 1 (Key), code 30 (A), value 0
Event: time 1238003651.881601, -------------- Report Sync ------------
^C

It appears that 'value 1' is key down, 'value 0' is key up, and 'value 2' is key repeated. So is this the kernel's fault, for sending a 'key repeated' message instead of a 'key down' followed by 'key up'?

Comment 3 Sam Morris 2009-03-25 11:14:27 UTC

I just rebooted and noticed that the first time I press the key, it is a 'value 1' event (key down). Subsequent presses are 'value 2' (key repeat). 'value 0' (key up) never happens.

Comment 4 Peter Hutterer 2009-03-26 21:11:53 UTC

Same cause as Bug 18590, this is a kernel bug.

*** This bug has been marked as a duplicate of bug 18590 ***

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