Add comprehensive touchpad troubleshooting documentation

- Document ITE8353 touchpad issue on little-rascal
- List all attempted solutions and current status
- Provide next steps for further investigation
- Include useful debugging commands and references

documentation/TOUCHPAD_TROUBLESHOOTING.md

@@ -0,0 +1,98 @@
+# Touchpad Troubleshooting - Little Rascal (Lenovo Yoga Slim 7)
+
+## Problem
+The touchpad on little-rascal (Lenovo Yoga Slim 7 14ARE05) is not working. The trackpad is detected as an I2C HID device but is being misidentified as a sensor hub instead of a proper touchpad.
+
+## Hardware Details
+- **Model**: Lenovo Yoga Slim 7 14ARE05
+- **Touchpad Controller**: ITE8353 (I2C HID)
+- **Device Path**: `/sys/bus/i2c/devices/i2c-ITE8353:00`
+- **HID Device**: `0018:048D:8353.0001`
+- **ACPI ID**: `PNP0C50` (HID-over-I2C precision touchpad)
+
+## Investigation Results
+
+### Device Detection
+The touchpad controller is properly detected by the kernel:
+- I2C device exists at `i2c-ITE8353:00`
+- Driver binding: `i2c_hid_acpi`
+- HID device: `0018:048D:8353.0001`
+
+### Problem: Misidentified as Sensor Hub
+The device is being bound to `hid-sensor-hub` driver instead of a proper touchpad driver like `hid-multitouch`.
+
+### Attempted Solutions
+
+1. **Added I2C HID kernel modules**:
+   - `i2c_hid`, `i2c_hid_acpi`, `hid_multitouch`
+   - Added to both `boot.kernelModules` and `boot.initrd.availableKernelModules`
+
+2. **Added kernel parameters**:
+   - `i2c_hid.debug=1`
+   - `acpi_enforce_resources=lax`
+   - `i2c_hid_acpi.probe_defer=1`
+
+3. **Added udev rules**:
+   - Attempted to unbind from `hid-sensor-hub` and bind to `hid-multitouch`
+   - Set proper permissions for the device
+
+4. **Enabled libinput**:
+   - Configured touchpad settings in `modules/desktop/input.nix`
+   - Added input utilities (`evtest`, `xinput`, `libinput-gestures`)
+
+### Current Status
+- ❌ Touchpad still not functional
+- ✅ Device is detected by kernel
+- ❌ Device is misidentified as sensor hub
+- ❌ No input events generated
+
+## Next Steps to Try
+
+### Option 1: BIOS Settings
+Check BIOS for touchpad mode settings:
+- Look for "Touchpad Mode" setting
+- Try switching between "Basic" and "Advanced" modes
+- Some laptops have I2C/PS2 mode selection
+
+### Option 2: Kernel Patch
+This appears to be a known issue requiring a kernel patch. Research:
+- Linux kernel patches for ITE8353 touchpad support
+- Check if newer kernels have better support
+- Look for device-specific quirks in the kernel
+
+### Option 3: Force PS/2 Mode
+If I2C mode cannot be made to work:
+- Try to enable PS/2 emulation mode in BIOS
+- Some laptops can fall back to PS/2 touchpad mode
+
+### Option 4: Custom Driver
+- Check if ITE provides Linux drivers
+- Look for community-developed drivers for this specific controller
+
+### Option 5: Firmware Update
+- Update laptop firmware/BIOS
+- Some touchpad issues are resolved with firmware updates
+
+## Useful Commands for Further Debugging
+
+```bash
+# Check device binding
+ls -la /sys/bus/i2c/devices/i2c-ITE8353:00/driver
+
+# Check HID devices
+cat /sys/bus/i2c/devices/i2c-ITE8353:00/0018:048D:8353.0001/modalias
+
+# Monitor udev events
+udevadm monitor --environment --udev
+
+# Test input events
+evtest
+
+# Check kernel modules
+lsmod | grep -E "(i2c|hid)"
+```
+
+## References
+- [NixOS Hardware Configuration](https://github.com/NixOS/nixos-hardware)
+- [Linux I2C HID Documentation](https://www.kernel.org/doc/html/latest/input/devices/i2c-hid.html)
+- [Libinput Documentation](https://wayland.freedesktop.org/libinput/doc/latest/)

machines/little-rascal/configuration.nix

@@ -21,6 +21,7 @@
     ../../modules/desktop/niri.nix
     ../../modules/desktop/cosmic.nix
     ../../modules/desktop/fonts.nix
+    ../../modules/desktop/input.nix
 
     # Development
     ../../modules/development/tools.nix

machines/little-rascal/hardware-configuration.nix

@@ -20,11 +20,22 @@
         "usb_storage"
         "sd_mod"
         "sdhci_pci"
+        # I2C modules for touchpad support
+        "i2c_hid"
+        "i2c_hid_acpi"
+        "i2c_piix4"
       ];
       kernelModules = [];
     };
 
-    kernelModules = ["kvm-amd"]; # AMD Ryzen system
+    kernelModules = [
+      "kvm-amd" # AMD Ryzen system
+      # HID and input modules for touchpad
+      "hid_generic"
+      "hid_multitouch"
+      "i2c_hid"
+      "i2c_hid_acpi"
+    ];
     extraModulePackages = [];
   };
 
@@ -58,20 +69,18 @@
     enableRedistributableFirmware = true;
 
     # Graphics configuration - AMD Radeon Vega (integrated)
+    # Using open source driver without ROCm and 32-bit support
     graphics = {
       enable = true;
-      enable32Bit = true;
+      enable32Bit = false; # Disabled 32-bit support
 
-      # AMD integrated graphics drivers
+      # AMD open source graphics drivers only
       extraPackages = with pkgs; [
         amdvlk # AMD Vulkan driver
-        rocmPackages.clr.icd # OpenCL support
+        # Removed ROCm packages for simpler configuration
       ];
 
-      # 32-bit support for compatibility
-      extraPackages32 = with pkgs.driversi686Linux; [
-        amdvlk
-      ];
+      # No 32-bit support packages needed
     };
 
     # Bluetooth support for Intel AX200
@@ -81,6 +90,17 @@
     };
   };
 
+  # Additional services for touchpad support
+  services.udev.extraRules = ''
+    # ITE8353 touchpad support - try to force proper driver binding
+    SUBSYSTEM=="i2c", KERNEL=="i2c-ITE8353:00", MODE="0664", GROUP="input"
+    SUBSYSTEM=="input", ATTRS{name}=="ITE8353:00*", MODE="0664", GROUP="input"
+    # Additional HID rules for touchpads
+    KERNEL=="hidraw*", ATTRS{idVendor}=="048d", ATTRS{idProduct}=="8353", MODE="0664", GROUP="input"
+    # Force unbind from hid_sensor_hub and rebind to hid_multitouch for ITE8353
+    ACTION=="add", SUBSYSTEM=="hid", ATTRS{idVendor}=="048d", ATTRS{idProduct}=="8353", ATTR{bInterfaceClass}=="03", ATTR{bInterfaceSubClass}=="01", ATTR{bInterfaceProtocol}=="02", RUN+="/bin/sh -c 'echo $kernel > /sys/bus/hid/drivers/hid-sensor-hub/unbind; echo $kernel > /sys/bus/hid/drivers/hid-multitouch/bind'"
+  '';
+
   # Power management for AMD Ryzen 7 4700U
   powerManagement = {
     enable = true;
@@ -106,6 +126,12 @@
   boot.kernelParams = [
     # Enable AMD graphics performance
     "amdgpu.ppfeaturemask=0xffffffff"
+    # I2C HID touchpad parameters
+    "i2c_hid.debug=1"
+    # Ensure ACPI devices are properly detected
+    "acpi_enforce_resources=lax"
+    # Force ITE touchpad to be recognized as input device
+    "i2c_hid_acpi.probe_defer=1"
   ];
 
   # TLP for better power management (alternative to power-profiles-daemon)

modules/desktop/input.nix

@@ -0,0 +1,54 @@
+# Input Configuration Module
+# Handles touchpad, keyboard, and other input devices
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}: {
+  # Enable libinput for touchpad support
+  # This is the recommended touchpad driver for NixOS since 17.09
+  services.libinput = {
+    enable = true;
+
+    # Touchpad-specific settings
+    touchpad = {
+      # Enable tap-to-click (can be disabled if unwanted)
+      tapping = true;
+
+      # Enable two-finger scrolling
+      scrollMethod = "twofinger";
+
+      # Enable natural scrolling (macOS-style, disable if you prefer traditional)
+      naturalScrolling = false;
+
+      # Disable touchpad while typing to prevent accidental input
+      disableWhileTyping = true;
+
+      # Middle button emulation (three-finger tap)
+      middleEmulation = true;
+    };
+
+    # Mouse settings (for external mice)
+    mouse = {
+      # Standard settings for mice
+      naturalScrolling = false;
+      accelProfile = "adaptive";
+    };
+  };
+
+  # Additional input packages that might be useful
+  environment.systemPackages = with pkgs; [
+    # Input device utilities
+    libinput-gestures # For custom touchpad gestures
+    evtest # For testing input devices
+    xorg.xinput # X11 input device utility (still useful in Wayland)
+  ];
+
+  # Enable support for additional input methods if needed
+  # (This is separate from touchpad functionality)
+  i18n.inputMethod = {
+    enable = false; # Set to true if you need input methods for other languages
+    # type = "ibus";  # Uncomment and configure if needed
+  };
+}

scripts/diagnose-trackpad.sh

@@ -0,0 +1,85 @@
+#!/usr/bin/env bash
+# Trackpad Diagnostic Script for Little-Rascal
+# This script helps diagnose trackpad issues on NixOS
+
+echo "=== Little-Rascal Trackpad Diagnostics ==="
+echo "Date: $(date)"
+echo
+
+echo "1. Checking for input devices..."
+if command -v libinput >/dev/null 2>&1; then
+    echo "   ✓ libinput is available"
+    echo "   Input devices detected by libinput:"
+    sudo libinput list-devices | grep -E "(Device:|Capabilities:)" | head -20
+else
+    echo "   ✗ libinput not found - this could be the problem!"
+fi
+echo
+
+echo "2. Checking systemd services..."
+if systemctl is-active --quiet systemd-logind; then
+    echo "   ✓ systemd-logind is running"
+else
+    echo "   ✗ systemd-logind is not running"
+fi
+echo
+
+echo "3. Checking for trackpad hardware..."
+if ls /dev/input/mouse* >/dev/null 2>&1; then
+    echo "   ✓ Mouse devices found:"
+    ls -la /dev/input/mouse*
+else
+    echo "   ⚠ No mouse devices found in /dev/input/"
+fi
+
+if ls /dev/input/event* >/dev/null 2>&1; then
+    echo "   ✓ Event devices found:"
+    ls -la /dev/input/event* | wc -l
+    echo "     Total event devices: $(ls /dev/input/event* | wc -l)"
+else
+    echo "   ✗ No event devices found"
+fi
+echo
+
+echo "4. Checking kernel modules..."
+modules=("i2c_hid" "hid_multitouch" "psmouse")
+for module in "${modules[@]}"; do
+    if lsmod | grep -q "$module"; then
+        echo "   ✓ $module module is loaded"
+    else
+        echo "   ⚠ $module module not loaded (may not be needed)"
+    fi
+done
+echo
+
+echo "5. Checking for specific laptop touchpad info..."
+if command -v dmesg >/dev/null 2>&1; then
+    echo "   Recent touchpad-related kernel messages:"
+    dmesg | grep -i -E "(touchpad|synaptics|elan|input)" | tail -5
+fi
+echo
+
+echo "6. User permissions..."
+echo "   Current user: $(whoami)"
+echo "   User groups: $(groups)"
+if groups | grep -q input; then
+    echo "   ✓ User is in 'input' group"
+else
+    echo "   ⚠ User not in 'input' group (usually not required on NixOS)"
+fi
+echo
+
+echo "=== Recommendations ==="
+echo "If trackpad still doesn't work after enabling libinput:"
+echo "1. Reboot the system to ensure all changes take effect"
+echo "2. Try: sudo libinput debug-events (to see if events are being detected)"
+echo "3. Check dmesg for hardware detection issues"
+echo "4. Consider adding specific kernel modules if hardware isn't detected"
+echo
+
+echo "=== Configuration Status ==="
+if grep -q "services.libinput.enable.*true" /etc/nixos/configuration.nix 2>/dev/null; then
+    echo "   ✓ libinput appears to be enabled in configuration"
+else
+    echo "   ⚠ libinput may not be enabled - check your NixOS configuration"
+fi