From 30a552991b81cef1eb5eae1aa3937b960b6e0f08 Mon Sep 17 00:00:00 2001
From: gdisirio <gdisirio@35acf78f-673a-0410-8e92-d51de3d6d3f4>
Date: Sun, 28 Apr 2013 13:27:37 +0000
Subject: [PATCH] Fixed bug #406.

git-svn-id: svn://svn.code.sf.net/p/chibios/svn/trunk@5638 35acf78f-673a-0410-8e92-d51de3d6d3f4
---
 os/hal/include/usb.h | 3 ++-
 os/hal/src/usb.c     | 7 ++++---
 readme.txt           | 2 ++
 3 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/os/hal/include/usb.h b/os/hal/include/usb.h
index 8d3bcde6b..6f18d7c55 100644
--- a/os/hal/include/usb.h
+++ b/os/hal/include/usb.h
@@ -249,7 +249,8 @@ typedef enum {
  */
 typedef enum {
   USB_EP0_WAITING_SETUP,                /**< Waiting for SETUP data.        */
-  USB_EP0_TX,                           /**< Transmitting.                  */
+  USB_EP0_TX,                           /**< Trasmitting.                   */
+  USB_EP0_WAITING_TX0,                  /**< Waiting transmit 0             */
   USB_EP0_WAITING_STS,                  /**< Waiting status.                */
   USB_EP0_RX,                           /**< Receiving.                     */
   USB_EP0_SENDING_STS,                  /**< Sending status.                */
diff --git a/os/hal/src/usb.c b/os/hal/src/usb.c
index 9c3825910..745b2d436 100644
--- a/os/hal/src/usb.c
+++ b/os/hal/src/usb.c
@@ -693,15 +693,16 @@ void _usb_ep0in(USBDriver *usbp, usbep_t ep) {
     /* If the transmitted size is less than the requested size and it is a
        multiple of the maximum packet size then a zero size packet must be
        transmitted.*/
-    if ((usbp->ep0n < max) &&
-        ((usbp->ep0n % usbp->epc[0]->in_maxsize) == 0)) {
+    if ((usbp->ep0n < max) && ((usbp->ep0n % usbp->epc[0]->in_maxsize) == 0)) {
       usbPrepareTransmit(usbp, 0, NULL, 0);
       chSysLockFromIsr();
       usbStartTransmitI(usbp, 0);
       chSysUnlockFromIsr();
+      usbp->ep0state = USB_EP0_WAITING_TX0;
       return;
     }
-
+    /* Falls into, it is intentional.*/
+  case USB_EP0_WAITING_TX0:
     /* Transmit phase over, receiving the zero sized status packet.*/
     usbp->ep0state = USB_EP0_WAITING_STS;
     usbPrepareReceive(usbp, 0, NULL, 0);
diff --git a/readme.txt b/readme.txt
index 7b36831e1..9547ba4b9 100644
--- a/readme.txt
+++ b/readme.txt
@@ -89,6 +89,8 @@
 *****************************************************************************
 
 *** 2.5.2 ***
+- FIX: Fixed USB driver possible deadlock under certain configurations (bug
+  #406)(backported to 2.4.4).
 - FIX: Fixed USB driver cannot be stopped (bug #405)(backported to 2.4.4).
 - FIX: Fixed several spelling errors (bug #404).
 - FIX: Fixed serial port in STM32F3 discovery test case (bug #402).