Add fix command and troubleshooting for errno=16 error

- Add 'fix' command to diagnose CEC connection issues
- Add detailed troubleshooting section for common errors
- Fix handles errno=16 (device busy) by checking processes and trying sudo
- Document solutions for CEC permission and connection issues

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

README.md

@@ -37,6 +37,7 @@ chmod +x cec-control.sh
 | `scan` | Scan for CEC devices | `./cec-control.sh scan` |
 | `status` | Show CEC adapter status | `./cec-control.sh status` |
 | `info` | Show TV information | `./cec-control.sh info` |
+| `fix` | Troubleshoot connection issues | `./cec-control.sh fix` |
 | `raw <command>` | Send raw CEC command | `./cec-control.sh raw 4f:82:10:00` |
 | `help` | Show help message | `./cec-control.sh help` |
 
@@ -55,9 +56,48 @@ chmod +x cec-control.sh
 
 ## Troubleshooting
 
-- **CEC not working**: Make sure CEC is enabled in your TV settings
-- **Permission denied**: Run with `sudo` if needed
-- **Device not found**: Check HDMI connection and try rescanning with `scan` command
+### Common Issues
+
+**ioctl CEC_S_MODE failed - errno=16 (Device or resource busy)**
+
+This error means something else is using the CEC device. Try these solutions:
+
+1. Run the built-in fix command:
+```bash
+./cec-control.sh fix
+```
+
+2. Kill any existing CEC processes:
+```bash
+sudo killall cec-client
+```
+
+3. Check what's using the device:
+```bash
+sudo lsof /dev/cec0
+```
+
+4. Try running with sudo:
+```bash
+sudo ./cec-control.sh scan
+```
+
+5. If using Kodi or LibreELEC, CEC may be enabled in the application. Disable it or stop the application first.
+
+**CEC not working**
+- Make sure CEC is enabled in your TV settings (often called "HDMI Control", "CEC Control", or branded names like "Bravia Link", "Anynet+", etc.)
+- Try a different HDMI port on your TV
+- Check that the HDMI cable is properly connected
+
+**Permission denied**
+- Add your user to the `video` group: `sudo usermod -aG video $USER`
+- Then log out and back in
+- Or run with `sudo`
+
+**Device not found**
+- Check if `/dev/cec0` exists: `ls -l /dev/cec0`
+- Ensure `cec-utils` is installed
+- Try rebooting the Pi
 
 ## Advanced Usage
 

cec-control.sh

@@ -41,6 +41,7 @@ Commands:
   scan                     Scan for CEC devices
   status                   Show CEC adapter status
   info                     Show TV information
+  fix                      Troubleshoot connection issues
 
   raw <command>            Send raw CEC command (hex)
 
@@ -136,6 +137,46 @@ raw_command() {
     send_command "tx $cmd"
 }
 
+fix_connection() {
+    echo "Attempting to fix CEC connection issues..."
+    echo ""
+
+    # Check if running as root
+    if [ "$EUID" -ne 0 ]; then
+        echo "Checking for existing CEC processes..."
+        pgrep -a cec-client || echo "No cec-client processes found"
+        echo ""
+        echo "Trying with sudo - you may need to enter your password:"
+        echo ""
+        sudo "$0" "$@"
+        exit $?
+    fi
+
+    echo "Running as root - checking CEC device status..."
+    echo ""
+
+    # Check if device exists
+    if [ -e /dev/cec0 ]; then
+        echo "CEC device /dev/cec0 exists"
+        ls -l /dev/cec0
+        echo ""
+
+        # Check what's using the device
+        echo "Checking what's using the CEC device:"
+        lsof /dev/cec0 2>/dev/null || echo "Nothing is locking /dev/cec0"
+        echo ""
+    else
+        echo "Warning: /dev/cec0 does not exist"
+        echo "Available devices:"
+        ls -la /dev/cec* /dev/tty* 2>/dev/null | grep -E "cec|ttyAMA|ttyS0" || echo "No CEC devices found"
+        echo ""
+    fi
+
+    echo "Attempting to scan for devices..."
+    echo ""
+    $CEC_CLIENT -s -d 1 < /dev/null
+}
+
 # Main script logic
 case "$1" in
     tv-on)
@@ -174,6 +215,9 @@ case "$1" in
     info)
         show_info
         ;;
+    fix)
+        fix_connection
+        ;;
     raw)
         raw_command "$2"
         ;;