Fix USB endpoint read with no data (thanks nox771)

http://forum.pjrc.com/threads/24726-Teensy-3-0-Serial-available%28%29-bug?p=42926&viewfull=1#post42926
PaulStoffregen · Feb 27, 2014 · 482a1f2 · 482a1f2
1 parent a781e92
commit 482a1f2
Showing 1 changed file with 4 additions and 2 deletions.
diff --git a/teensy3/usb_dev.c b/teensy3/usb_dev.c
@@ -529,8 +529,10 @@ usb_packet_t *usb_rx(uint32_t endpoint)
 	if (endpoint >= NUM_ENDPOINTS) return NULL;
 	__disable_irq();
 	ret = rx_first[endpoint];
-	if (ret) rx_first[endpoint] = ret->next;
-	usb_rx_byte_count_data[endpoint] -= ret->len;
+	if (ret) {
+		rx_first[endpoint] = ret->next;
+		usb_rx_byte_count_data[endpoint] -= ret->len;
+	}
 	__enable_irq();
 	//serial_print("rx, epidx=");
 	//serial_phex(endpoint);