3 files changed, 23 insertions, 67 deletions
diff --git a/src/class/mtp/mtp.h b/src/class/mtp/mtp.h
index 7b22837cd..75af8baf8 100644
--- a/src/class/mtp/mtp.h
+++ b/src/class/mtp/mtp.h
@@ -1,25 +1,7 @@
 /*
- * The MIT License (MIT)
- *
- * Copyright (c) 2025 Ennebi Elettronica (https://ennebielettronica.com)
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this software and associated documentation files (the "Software"), to deal
- * in the Software without restriction, including without limitation the rights
- * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- * copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in
- * all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
- * THE SOFTWARE.
+ * SPDX-FileCopyrightText: Copyright (c) 2025 Ennebi Elettronica (https://ennebielettronica.com)
+ * SPDX-FileCopyrightText: Copyright (c) 2025 Ha Thach (tinyusb.org)
+ * SPDX-License-Identifier: MIT
  *
  * This file is part of the TinyUSB stack.
  */
diff --git a/src/class/mtp/mtp_device.c b/src/class/mtp/mtp_device.c
index 1f76dfcc7..275c9f858 100644
--- a/src/class/mtp/mtp_device.c
+++ b/src/class/mtp/mtp_device.c
@@ -1,25 +1,7 @@
 /*
- * The MIT License (MIT)
- *
- * Copyright (c) 2025 Ennebi Elettronica (https://ennebielettronica.com)
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this software and associated documentation files (the "Software"), to deal
- * in the Software without restriction, including without limitation the rights
- * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- * copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in
- * all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
- * THE SOFTWARE.
+ * SPDX-FileCopyrightText: Copyright (c) 2025 Ennebi Elettronica (https://ennebielettronica.com)
+ * SPDX-FileCopyrightText: Copyright (c) 2025 Ha Thach (tinyusb.org)
+ * SPDX-License-Identifier: MIT
  *
  * This file is part of the TinyUSB stack.
  */
@@ -455,8 +437,11 @@ bool mtpd_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t event, uint32_t
       TU_LOG_DRV("  MTP Data %s CB: xferred_bytes=%lu, xferred_len/total_len=%lu/%lu, is_complete=%d\r\n",
                  is_data_in ? "IN" : "OUT", xferred_bytes, p_mtp->xferred_len, p_mtp->total_len, is_complete ? 1 : 0);
 
-      // Send/queue ZLP if packet is full-sized but transfer is complete
-      if (is_complete && xferred_bytes > 0 && !(xferred_bytes & (threshold - 1))) {
+      // Send/queue ZLP if packet is full-sized but transfer is complete.
+      // OUT must deliver this final payload to the application before receiving
+      // its terminating ZLP below.
+      const bool need_zlp = is_complete && xferred_bytes > 0 && !(xferred_bytes & (threshold - 1));
+      if (is_data_in && need_zlp) {
         TU_LOG_DRV("  queue ZLP\r\n");
         TU_VERIFY(usbd_edpt_claim(p_mtp->rhport, ep_addr));
         TU_ASSERT(usbd_edpt_xfer(p_mtp->rhport, ep_addr, NULL, 0, false));
@@ -484,9 +469,16 @@ bool mtpd_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t event, uint32_t
           cb_data.io_container = headerless_packet;
           cb_data.io_container.payload_bytes = xferred_bytes;
         }
-        tud_mtp_data_xfer_cb(&cb_data);
+        if (xferred_bytes > 0) {
+          tud_mtp_data_xfer_cb(&cb_data);
+        }
 
-        if (is_complete) {
+        if (need_zlp) {
+          TU_LOG_DRV("  queue ZLP\r\n");
+          TU_VERIFY(usbd_edpt_claim(p_mtp->rhport, ep_addr));
+          TU_ASSERT(usbd_edpt_xfer(p_mtp->rhport, ep_addr, NULL, 0, false));
+          return true;
+        } else if (is_complete) {
           // back to header + payload for response
           cb_data.io_container = headered_packet;
           cb_data.io_container.header->len = sizeof(mtp_container_header_t);
diff --git a/src/class/mtp/mtp_device.h b/src/class/mtp/mtp_device.h
index f2c5cef7f..b2c4f1e04 100644
--- a/src/class/mtp/mtp_device.h
+++ b/src/class/mtp/mtp_device.h
@@ -1,25 +1,7 @@
 /*
- * The MIT License (MIT)
- *
- * Copyright (c) 2025 Ennebi Elettronica (https://ennebielettronica.com)
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this software and associated documentation files (the "Software"), to deal
- * in the Software without restriction, including without limitation the rights
- * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- * copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in
- * all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
- * THE SOFTWARE.
+ * SPDX-FileCopyrightText: Copyright (c) 2025 Ennebi Elettronica (https://ennebielettronica.com)
+ * SPDX-FileCopyrightText: Copyright (c) 2025 Ha Thach (tinyusb.org)
+ * SPDX-License-Identifier: MIT
  *
  * This file is part of the TinyUSB stack.
  */