Handle OUT transfer completion in MTP

Handle OUT transfer differently from IN to not prematurely change MTP phase when host sends short packet that is not end of MTP data phase. Only reaching container length or ZLP should change phase.

1 files changed, 13 insertions, 3 deletions

diff --git a/src/class/mtp/mtp_device.c b/src/class/mtp/mtp_device.c
index 0da984f4a..fd06b4601 100644
--- a/src/class/mtp/mtp_device.c
+++ b/src/class/mtp/mtp_device.c
@@ -441,9 +441,19 @@ bool mtpd_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t event, uint32_t
         threshold = CFG_TUD_MTP_EP_BUFSIZE;
       }
 
-      // Check completion: ZLP, short packet, or total length reached
-      const bool is_complete =
-        (xferred_bytes == 0 || xferred_bytes < threshold || p_mtp->xferred_len >= p_mtp->total_len);
+      // Check completion for IN and OUT separately
+      bool is_complete;
+
+      if (is_data_in)
+      {
+        // IN completion: short packet, ZLP, or reaching total_len
+        is_complete = (xferred_bytes == 0 || xferred_bytes < threshold || p_mtp->xferred_len >= p_mtp->total_len);
+      }
+      else
+      {
+        // OUT completion: reaching total_len or ZLP
+        is_complete = (p_mtp->xferred_len >= p_mtp->total_len) || ((xferred_bytes == 0 && p_mtp->xferred_len > 0));
+      }
 
       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);