pmci: mctp: Fix MCTP USB Packet Length Issue

According to DSP0283 1.0.1, Length byte in MCTP over USB header
fields should start from the "MCTP over USB Header" to the last
byte in the "MCTP packet payload"

Signed-off-by: John Chung <[email protected]>

Author: gtossk2

samples/subsys/pmci/mctp/usb_endpoint/usb_host_tester.py

@@ -69,14 +69,14 @@ def disconnect(self):
 
         print("Sending message with size smaller than USB FS MPS (<64b)")
         usb_dev.send_data(
-            b'\x1a\xb4\x00\x0f\x01\x0a\x14\xc0\x48\x65\x6c\x6c\x6f\x2c\x20\x4d\x43\x58\x00'
+            b'\x1a\xb4\x00\x13\x01\x0a\x14\xc0\x48\x65\x6c\x6c\x6f\x2c\x20\x4d\x43\x58\x00'
         )
         response = usb_dev.receive_data()
         print("Received:", bytes(response))
 
         print("Sending message spanning two USB FS packets (>64b)")
         usb_dev.send_data(
-            b'\x1a\xb4\x00\x4c\x01\x0a\x14\xc0\x48\x65\x6c\x6c\x6f\x2c\x20\x4d\x43\x58\x2e\x20'
+            b'\x1a\xb4\x00\x50\x01\x0a\x14\xc0\x48\x65\x6c\x6c\x6f\x2c\x20\x4d\x43\x58\x2e\x20'
             b'\x4c\x65\x74\x27\x73\x20\x74\x65\x73\x74\x20\x61\x20\x6d\x75\x6c\x74\x69\x2d\x70'
             b'\x61\x63\x6b\x65\x74\x20\x6d\x65\x73\x73\x61\x67\x65\x20\x74\x6f\x20\x73\x65\x65'
             b'\x20\x68\x6f\x77\x20\x79\x6f\x75\x20\x68\x61\x6e\x64\x6c\x65\x20\x69\x74\x2e\x00'
@@ -86,8 +86,8 @@ def disconnect(self):
 
         print("Sending message with two MCTP messages in a single USB FS packet")
         usb_dev.send_data(
-            b'\x1a\xb4\x00\x12\x01\x0a\x14\xc0\x48\x65\x6c\x6c\x6f\x2c\x20\x4d\x43\x58\x2c\x20'
-            b'\x31\x00\x1a\xb4\x00\x12\x01\x0a\x14\xc0\x48\x65\x6c\x6c\x6f\x2c\x20\x4d\x43\x58'
+            b'\x1a\xb4\x00\x16\x01\x0a\x14\xc0\x48\x65\x6c\x6c\x6f\x2c\x20\x4d\x43\x58\x2c\x20'
+            b'\x31\x00\x1a\xb4\x00\x16\x01\x0a\x14\xc0\x48\x65\x6c\x6c\x6f\x2c\x20\x4d\x43\x58'
             b'\x2c\x20\x32\x00'
         )
         response = usb_dev.receive_data()

subsys/pmci/mctp/mctp_usb.c

@@ -128,7 +128,7 @@ int mctp_usb_tx(struct mctp_binding *binding, struct mctp_pktbuf *pkt)
 	usb->tx_buf[0] = MCTP_USB_DMTF_0;
 	usb->tx_buf[1] = MCTP_USB_DMTF_1;
 	usb->tx_buf[2] = 0;
-	usb->tx_buf[3] = len;
+	usb->tx_buf[3] = len + MCTP_USB_HEADER_SIZE;
 
 	memcpy((void *)&usb->tx_buf[MCTP_USB_HEADER_SIZE], pkt->data, len);
 
@@ -244,7 +244,8 @@ static void mctp_usb_class_out_work(struct k_work *work)
 			}
 
 			usb->rx_data_idx = 0;
-			usb->rx_pkt = mctp_pktbuf_alloc(&usb->binding, ctx->out_buf[i]);
+			usb->rx_pkt = mctp_pktbuf_alloc(&usb->binding,
+							ctx->out_buf[i] - MCTP_USB_HEADER_SIZE);
 			if (usb->rx_pkt == NULL) {
 				LOG_ERR("Could not allocate PKT buffer");
 				mctp_usb_reset_rx_state(usb);
@@ -253,7 +254,7 @@ static void mctp_usb_class_out_work(struct k_work *work)
 
 			usb->rx_state = STATE_DATA;
 
-			LOG_DBG("Expecting LEN=%d", (int)ctx->out_buf[i]);
+			LOG_DBG("Expecting LEN=%d", (int)ctx->out_buf[i] - MCTP_USB_HEADER_SIZE);
 
 			break;
 		}