EliteBook cursor drifting on Linux – Pointing Stick / TrackPoint cause and permanent fix

[sauravsvt]

I experienced a very similar cursor-drift problem on my HP EliteBook under Linux.

The cursor would start moving upward by itself, fight against normal touchpad movement, and sometimes feel as if the touchpad was freezing.

Initially, reloading the I2C HID drivers fixed the problem temporarily:

```bash
sudo modprobe -r i2c_hid_acpi i2c_hid
sudo modprobe i2c_hid_acpi i2c_hid
```

However, after a few minutes the cursor drift would return.

After troubleshooting the Linux input devices, I discovered that the touchpad itself was not the problem. The Pointing Stick / TrackPoint was generating unwanted movement events.

I tested this by inhibiting only the pointing-stick input devices:

```bash
echo 1 | sudo tee /sys/class/input/inputXX/inhibited
```

After disabling the pointing stick, the cursor immediately became completely stable and the touchpad continued working normally.

Important: do not copy `inputXX` from another computer because Linux input numbers can change between systems and reboots.

For a permanent solution, I created:

```bash
/etc/udev/rules.d/99-disable-pointingstick.rules
```

with:

```udev
ACTION!="remove", SUBSYSTEM=="input", KERNEL=="input*", ENV{ID_INPUT_POINTINGSTICK}=="1", ATTR{inhibited}="1"
ACTION!="remove", KERNEL=="event*", ENV{ID_INPUT_POINTINGSTICK}=="1", ENV{LIBINPUT_IGNORE_DEVICE}="1"
```

Then applied it with:

```bash
sudo udevadm control --reload-rules
sudo udevadm trigger
```

This disables only devices identified by Linux as a pointing stick while leaving the actual touchpad enabled.

After applying this fix, the cursor drift completely stopped.

I am posting this because I found older EliteBook reports describing very similar symptoms, where the problem appears to be the pointing stick rather than the touchpad itself.

If someone has the same issue, I recommend first identifying the pointing-stick device and testing by disabling it temporarily before changing or replacing the touchpad.