usb-device-mtp: Fix vendor extension and device identification.

Adds proper Microsoft MTP vendor extension ID and extension string
to ensure the device is correctly identified as MTP rather than PTP.
Also enhances device and storage identification with more complete
manufacturer, model, version and descriptive information.

🤖 Generated with [Claude Code](https://claude.ai/code)

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

Author: andrewleech

micropython/usb/usb-device-mtp/usb/device/mtp.py

@@ -461,6 +461,8 @@ def _process_data_phase(self, data):
 
     def _cmd_get_device_info(self):
         """Handle GetDeviceInfo command."""
+        print("[MTP] Generating device info response")
+        
         # Prepare the device info dataset
         data = bytearray(512)  # Pre-allocate buffer
         offset = 0
@@ -470,15 +472,22 @@ def _cmd_get_device_info(self):
         offset += 2
 
         # MTP vendor extension ID
-        struct.pack_into("<I", data, offset, 0x00000000)  # No vendor extension
+        # Use Microsoft's extension ID to better identify as a true MTP device
+        struct.pack_into("<I", data, offset, 0x00000006)  # Microsoft MTP Extension
         offset += 4
 
         # MTP version
         struct.pack_into("<H", data, offset, 100)  # Version 1.00
         offset += 2
 
-        # MTP extensions (empty string)
-        struct.pack_into("<H", data, offset, 0)  # No extension string
+        # MTP extensions description string
+        ext_string = "microsoft.com: 1.0"  # Standard Microsoft extension string
+        struct.pack_into("<H", data, offset, len(ext_string) + 1)  # String length including null terminator
+        offset += 2
+        for c in ext_string:
+            struct.pack_into("<H", data, offset, ord(c))
+            offset += 2
+        struct.pack_into("<H", data, offset, 0)  # Null terminator
         offset += 2
 
         # Functional mode
@@ -530,12 +539,18 @@ def _cmd_get_device_info(self):
             struct.pack_into("<H", data, offset, fmt)
             offset += 2
 
-        # Manufacturer (empty string)
-        struct.pack_into("<H", data, offset, 0)
+        # Manufacturer
+        manufacturer = "MicroPython"
+        struct.pack_into("<H", data, offset, len(manufacturer) + 1)
+        offset += 2
+        for c in manufacturer:
+            struct.pack_into("<H", data, offset, ord(c))
+            offset += 2
+        struct.pack_into("<H", data, offset, 0)  # Null terminator
         offset += 2
 
-        # Model (MicroPython)
-        model = "MicroPython"
+        # Model
+        model = "MicroPython MTP Device"
         struct.pack_into("<H", data, offset, len(model) + 1)
         offset += 2
         for c in model:
@@ -544,12 +559,24 @@ def _cmd_get_device_info(self):
         struct.pack_into("<H", data, offset, 0)  # Null terminator
         offset += 2
 
-        # Device version (empty string)
-        struct.pack_into("<H", data, offset, 0)
+        # Device version
+        version = "1.0"
+        struct.pack_into("<H", data, offset, len(version) + 1)
+        offset += 2
+        for c in version:
+            struct.pack_into("<H", data, offset, ord(c))
+            offset += 2
+        struct.pack_into("<H", data, offset, 0)  # Null terminator
         offset += 2
 
-        # Serial number (empty string)
-        struct.pack_into("<H", data, offset, 0)
+        # Serial number
+        serial = "MP12345"  # Generic serial number
+        struct.pack_into("<H", data, offset, len(serial) + 1)
+        offset += 2
+        for c in serial:
+            struct.pack_into("<H", data, offset, ord(c))
+            offset += 2
+        struct.pack_into("<H", data, offset, 0)  # Null terminator
         offset += 2
 
         # Send the device info
@@ -603,7 +630,10 @@ def _cmd_get_storage_ids(self):
 
     def _cmd_get_storage_info(self, params):
         """Handle GetStorageInfo command."""
+        print("[MTP] Generating storage info for storage ID: 0x{:08x}".format(params[0] if params else 0))
+        
         if not params or params[0] != self._storage_id:
+            print("[MTP] Invalid storage ID requested: 0x{:08x}".format(params[0] if params else 0))
             self._send_response(_MTP_RESPONSE_INVALID_STORAGE_ID)
             return
 
@@ -612,8 +642,10 @@ def _cmd_get_storage_info(self, params):
             fs_stat = os.statvfs(self._storage_path)
             free_bytes = fs_stat[0] * fs_stat[4]  # f_bsize * f_bavail
             total_bytes = fs_stat[0] * fs_stat[2]  # f_bsize * f_blocks
-        except:
+            print("[MTP] Storage stats: total={} bytes, free={} bytes".format(total_bytes, free_bytes))
+        except Exception as e:
             # If we can't get stats, just return reasonable defaults
+            print("[MTP] Error getting storage stats: {}".format(str(e)))
             free_bytes = 1024 * 1024  # 1MB
             total_bytes = 4 * 1024 * 1024  # 4MB
 
@@ -645,12 +677,18 @@ def _cmd_get_storage_info(self, params):
         struct.pack_into("<I", data, offset, 0xFFFFFFFF)
         offset += 4
 
-        # Storage description (empty)
-        struct.pack_into("<H", data, offset, 0)
+        # Storage description
+        desc = "MicroPython Flash Storage"
+        struct.pack_into("<H", data, offset, len(desc) + 1)
+        offset += 2
+        for c in desc:
+            struct.pack_into("<H", data, offset, ord(c))
+            offset += 2
+        struct.pack_into("<H", data, offset, 0)  # Null terminator
         offset += 2
 
         # Volume identifier (root)
-        volume_id = "MicroPython"
+        volume_id = "MicroPython Storage"
         struct.pack_into("<H", data, offset, len(volume_id) + 1)
         offset += 2
         for c in volume_id: