libusbhost: Save endpoint ID in usb_request struct

Change-Id: I2cf189cee67c2efbcf919c8bae1447a6cb112f02
Signed-off-by: Mike Lockwood <lockwood@android.com>

include/usbhost/usbhost.h

@@ -47,6 +47,7 @@ struct usb_request
     int actual_length;
     int max_packet_size;
     void *private_data; /* struct usbdevfs_urb* */
+    int endpoint;
     void *client_data;  /* free for use by client */
 };
 
@@ -185,7 +186,9 @@ int usb_device_control_transfer(struct usb_device *device,
                             int length,
                             unsigned int timeout);
 
-/* Reads or writes on a bulk endpoint */
+/* Reads or writes on a bulk endpoint.
+ * Returns number of bytes transferred, or negative value for error.
+ */
 int usb_device_bulk_transfer(struct usb_device *device,
                             int endpoint,
                             void* buffer,

libusbhost/usbhost.c

@@ -512,6 +512,7 @@ struct usb_request *usb_request_new(struct usb_device *dev,
     req->dev = dev;
     req->max_packet_size = __le16_to_cpu(ep_desc->wMaxPacketSize);
     req->private_data = urb;
+    req->endpoint = urb->endpoint;
     urb->usercontext = req;
 
     return req;