Mouse and keyboard don't work when used at the same time

Question

I am running the i3 window manager with Debian 9 Stretch on a laptop with a trackpad.

I have run into the problem that whenever I type, the mouse is disabled. Is this normal behavior or a bug?

nonfree repos have been enabled and linux-firmware-nonfree has been installed. The bug does not show up on other distributions.

This does not happen with a USB mouse

xinput output

Virtual core pointer                        id=2    [master pointer  (3)]
Virtual core XTEST pointer                  id=4    [slave  pointer  (2)]
ETPS/2 Elantech Touchpad                    id=11   [slave  pointer  (2)]

Virtual core keyboard                       id=3    [master keyboard (2)]
Virtual core XTEST keyboard                 id=5    [slave  keyboard (3)]
Video Bus                                   id=7    [slave  keyboard (3)]
Power Button                                id=8    [slave  keyboard (3)]
HP TrueVision HD                            id=9    [slave  keyboard (3)]
AT Translated Set 2 keyboard                id=10   [slave  keyboard (3)]
HP Wireless hotkeys                         id=12   [slave  keyboard (3)]
HP WMI hotkeys                              id=13   [slave  keyboard (3)]
Power Button                                id=6    [slave  keyboard (3)]

Touchpad Properties

Device 'ETPS/2 Elantech Touchpad':
    Device Enabled (142):   1
    Coordinate Transformation Matrix (144): 1.000000, 0.000000, 0.000000, 0.000000, 1.000000, 0.000000, 0.000000, 0.000000, 1.000000
    libinput Tapping Enabled (277): 0
    libinput Tapping Enabled Default (278): 0
    libinput Tapping Drag Enabled (279):    1
    libinput Tapping Drag Enabled Default (280):    1
    libinput Tapping Drag Lock Enabled (281):   0
    libinput Tapping Drag Lock Enabled Default (282):   0
    libinput Tapping Button Mapping Enabled (283):  1, 0
    libinput Tapping Button Mapping Default (284):  1, 0
    libinput Accel Speed (285): 0.000000
    libinput Accel Speed Default (286): 0.000000
    libinput Natural Scrolling Enabled (287):   0
    libinput Natural Scrolling Enabled Default (288):   0
    libinput Send Events Modes Available (262): 1, 1
    libinput Send Events Mode Enabled (263):    0, 0
    libinput Send Events Mode Enabled Default (264):    0, 0
    libinput Left Handed Enabled (289): 0
    libinput Left Handed Enabled Default (290): 0
    libinput Scroll Methods Available (291):    1, 1, 0
    libinput Scroll Method Enabled (292):   1, 0, 0
    libinput Scroll Method Enabled Default (293):   1, 0, 0
    libinput Disable While Typing Enabled (294):    1
    libinput Disable While Typing Enabled Default (295):    1
    Device Node (265):  "/dev/input/event1"
    Device Product ID (266):    2, 14
    libinput Drag Lock Buttons (296):   <no items>
    libinput Horizontal Scroll Enabled (297):   1

Answer 1

The problem I was having involved the Disable While Typing Enabled feature of my trackpad. These are the steps I used to solve it.

1. Make sure xinput is installed.

2. Type xinput to find the name of the trackpad device. Mine was ETPS/2 Elantech Touchpad.

3. Run xinput --list-props "DEVICE" to list the properties of the device.

4. Go through the list until you find something like Disable While Typing.

5. Use

   xinput --set-prop "DEVICE" ID_OF_PROPERTY 0
   

   For me, this was

   xinput --set-prop "ETPS/2 Elantech Touchpad" 294 0
   

Answer 2

For me, with XFCE on Debian 11 only the following worked:

1. Edit /usr/share/X11/xorg.conf.d/40-libinput.conf
2. Comment out Option "SendEventsMode" "disabled-on-external-mouse" under inputclass with identifier libinput touchpad catchall

Mine looked like this in end:

Section "InputClass"
    Identifier "libinput touchpad catchall"
    MatchIsTouchpad "on"
    MatchDevicePath "/dev/input/event*"
    Option "Tapping" "True"
    Option "TappingDrag" "True"
    Option "DisableWhileTyping" "True"
    Option "AccelProfile" "adaptive"
    Option "AccelSpeed" "0.4"
    #Option "SendEventsMode" "disabled-on-external-mouse"
    Driver "libinput"
EndSection

Note: I had also to restart X11 for this to take effect.