Per-device filtering

[roberto-chang-silva]

Hello! thanks for maccel it's working great for me overall.

I’m on CachyOS (Arch-based) + KDE Plasma on Wayland. The problem is that maccel seems to aply the configs to all pointing devices. I_normally have a mouse for gaming and a trackball for daily use.

Questions:

1. Does this support per-device configuration (whitelist/blacklist) so I can bind it to a specific device?
2. If yes, what is the recommended way to do it?
3. If no, is per-device filtering planned, or is this intentionally global by design?

[dougg0k]

Hey,

You can use udev or systemd service to detect a device change and run a command or script based on that. #49

❯ maccel --help                                                                                                                                                                                                                                                                    
CLI to control the parameters for the maccel driver

Usage: maccel [COMMAND]

Commands:
  set         Set the value for a parameter of the maccel driver
  get         Get the values for parameters of the maccel driver
...

Add a udev file to /usr/lib/udev/rules.d/, you could name the file 99-maccel-devices.rules

e.g.,

ACTION=="add", SUBSYSTEM=="input", ATTRS{idVendor}=="046d", ATTRS{idProduct}=="c539", \
RUN+="/usr/local/bin/maccel set all common 1.0 2.0 1600 0", \
RUN+="/usr/local/bin/maccel set mode linear", \
RUN+="/usr/local/bin/maccel set all linear 0.1 7.5 1.5"

You can alter the ids to your respective devices, to find the respective, use something like lsusb to get the ID vendor:product.

Set a rule per device that you want. Then it should auto detect them and apply the commands.

Use these to apply the udev file changes.

sudo udevadm control --reload-rules
sudo udevadm trigger

[roberto-chang-silva]

Thanks! I tested the udev-rule approach and it works as expected for applying a profile on device “add”.
The only issue I ran into is that in my setup both dongles are always plugged in (I just toggle the mouse/trackball power switch), so there isn’t a connect/disconnect event when I switch between them.
I originally thought there might be true per-device profiles while both devices are present at the same time. Thanks though! My current solution is to set the Natural profile while working and change to No acceleration when gaming.

[dougg0k]

I see.

I never used this kind of thing before (change based on mouse movement), so I asked an AI and there were more than one suggestion, but the one that require the least cpu usage is.

---

interception-tools — event-driven, not polling-based.

It intercepts input events at the kernel level and triggers commands only when events occur, with near-zero CPU overhead when idle.

Setup

Install:

sudo pacman -S interception-tools

Create /etc/interception/udevmon.yaml:

- devices:
    - name: Gaming Mouse
      phys: <your-gaming-mouse-phys>
  action: |
    maccel set mode no-accel
    
- devices:
    - name: Trackball
      phys: <your-trackball-phys>
  action: |
    maccel set mode natural

Find device phys identifiers:

cat /proc/bus/input/devices | grep -A5 "Gaming Mouse\|Trackball"

Enable:

sudo systemctl enable --now udevmon

Trade-off: Requires learning interception-tools config; setup is one-time.

CPU usage: Essentially zero when idle. Only activates on actual input events. More efficient than polling or stream-parsing.

This is the minimal-overhead solution without sacrificing automation.

Note: There may be better ways to set it up - Check the README https://gitlab.com/interception/linux/tools

---

The other two suggestions were the following.

Option 1: Daemon monitoring specific devices (most direct)

Create a script that watches which device is actively sending input and switches profiles:

#!/bin/bash

# Monitor which device has recent activity and switch profiles
while true; do
    # Check which device had input in the last second
    GAMING_MOUSE="/dev/input/event4"      # Replace with your device
    TRACKBALL="/dev/input/event5"         # Replace with your device
    
    GAMING_TIME=$(stat -c %Y "$GAMING_MOUSE" 2>/dev/null || echo 0)
    TRACKBALL_TIME=$(stat -c %Y "$TRACKBALL" 2>/dev/null || echo 0)
    
    if [ "$GAMING_TIME" -gt "$TRACKBALL_TIME" ]; then
        maccel set mode no-accel
    else
        maccel set mode natural
    fi
    
    sleep 1
done

Run as a systemd service for persistence.

Trade-off: Simple but constantly polling; high CPU if update frequency is fast.

Option 2: Use libinput debug-events with per-device filtering

libinput debug-events --device /dev/input/eventX | while read line; do
    if [[ $line == *"POINTER_MOTION"* ]]; then
        maccel set mode no-accel  # Gaming profile
    fi
done

Trade-off: Better than polling, but requires parsing event stream; loses context about which device if both generate motion simultaneously.