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I have a puzzle: 1) Debian 4.9.65 system 2) Microsoft Natural Keyboard 4000 3) Acer monitor working as USB hub

When the keyboard is plugged to the monitor's USB hub, it mostly works, visible in lsusb as Microsoft ... 4000 V1.0, however none of the multimedia keys work.

If I plug the keyboard directly to PC, without changing any configuration, the multimedia keys just work, without me doing anything.

[Update] Found out it also depends on USB ports in the hub. If I swap keyboard and mouse, multimedia keys work when plugged into USB hub.

Here are the two devices plugged into this USB port (Microsoft keyboard shows up as two devices - regular keys are reported by first one, multimedia keys by second one). If the order reported by evtest command is

/dev/input/event3:  Microsoft Natural® Ergonomic Keyboard 4000
/dev/input/event4:  Microsoft Natural® Ergonomic Keyboard 4000
/dev/input/event5:  Evoluent VerticalMouse 4

then the multimedia keys don't work.

If the order is

/dev/input/event3:  Evoluent VerticalMouse 4
/dev/input/event4:  Microsoft Natural® Ergonomic Keyboard 4000
/dev/input/event5:  Microsoft Natural® Ergonomic Keyboard 4000

the multimedia keys do work.

So the USB hub works, but something is filtering out or ignoring multimedia keys if the keyboard is plugged into the first port of USB hub. What part of software or hardware might be doing this?

  • Can you see the key presses with evtest? – imbuedHope Jan 19 '18 at 3:09
  • when plugged directly - yes. when plugged in USB hub - no. – Michael Jan 19 '18 at 18:45
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    i think a defect in the hub is more likely than an OS-level issue. test with other hubs if available, with other devices in the suspect port, etc. – quixotic Jan 19 '18 at 20:22
  • Please edit question with the additional lines in dmesg after you plug in the keyboard, in both configurations (working and not working). – dirkt Jan 19 '18 at 22:50

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