Technically, it means "your connection is not reliable." De-bouncing is a trick in reading keyboards that takes the first few microseconds of "key down" connection and ignores them, because contacts may "bounce" on and off when the key is travelling under finger pressure. That prevents the sudden shift on-off-on-off-on-off that may occur when the two contacts are nearly in full contact...but not quite yet, from being perceived as multiple keystrokes.
When you plug in a USB device, the drivers similarly do some filtering (ideally in hardware, but potentially in software) to make sure the USB contacts are all firmly made before accepting any input or trusting the connection for output. If you have a faulty connector (on either side), you may find that the "bouncing" is so pronounced that the incoming queue of signals is filled up...which might account for it "settling down" after 45 seconds or so.
1. Make sure the USB connections (both ends, and both sides of each connection) are tight an firm. 2. Try a different USB cable between the equipment and your computer. 3. Try connecting a different device, and see if the problem lies in your USB external device. 4. Confirm the device/cable combination work with another computer without same kind of problem (to rule out those external components).
If all this doesn't solve the problem, then you may have an inappropriate Bluetooth driver and/or need to configure some "bounce" parameters.
The only real way to see the "bounce" is with a storage oscilloscope, which is triggered on the first "contact" and stores for a second or so. Then you can actually "see" the waveshape of the "bouncing" and that can help you isolate its' cause.
--Carol Anne
-----Original Message----- From: centos-bounces@centos.org [mailto:centos-bounces@centos.org] On Behalf Of Scott Silva Sent: Monday, January 14, 2008 12:48 PM To: centos@centos.org Subject: [CentOS] Re: What is connect-debounce wrt usb?
on 1/14/2008 11:55 AM Robert Moskowitz spake the following:
I get the following message on a Centos 5 system (really a
Trixbox 2.4
build on Centos 5):
Jan 14 00:12:28 sip2 kernel: hub 1-0:1.0: connect-debounce failed, port 1 disabled
What does this mean?
This message occurs about 30 times/sec for about 45 sec. Then my Bluetooth token starts up.
Your USB device or its cable has a poor connection. Can you try it in another port? The debouncing is supposed to cover for the rapid make-break that would appear to the system as you plug/unplug a device. Yours seems to have a less than tight connection, and that is why you get the debounce errors. It could be a loose port or a bad cable at either end.
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