diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
index 80ccfa1..74cc3c8 100644
--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -95,6 +95,7 @@
 	unsigned long tx_bytes;
 	unsigned long tx_outstanding_bytes;
 	unsigned long tx_outstanding_urbs;
+	unsigned short max_packet_size;
 };
 
 /* struct ftdi_sio_quirk is used by devices requiring special attention. */
@@ -703,7 +704,6 @@
 
 /* Constants for read urb and write urb */
 #define BUFSZ 512
-#define PKTSZ 64
 
 /* rx_flags */
 #define THROTTLED		0x01
@@ -1296,6 +1296,45 @@
 }
 
 
+/* Determine the maximum packet size for the device.  This depends on the chip
+ * type and the USB host capabilities.  The value should be obtained from the
+ * device descriptor as the chip will use the appropriate values for the host.*/
+static void ftdi_set_max_packet_size(struct usb_serial_port *port)
+{
+	struct ftdi_private *priv = usb_get_serial_port_data(port);
+	struct usb_serial *serial = port->serial;
+	struct usb_device *udev = serial->dev;
+
+	struct usb_interface *interface = serial->interface;
+	struct usb_endpoint_descriptor *ep_desc = &interface->cur_altsetting->endpoint[1].desc;
+
+	unsigned num_endpoints;
+	int i = 0;
+
+	num_endpoints = interface->cur_altsetting->desc.bNumEndpoints;
+	dev_info(&udev->dev, "Number of endpoints %d\n", num_endpoints);
+
+	/* NOTE: some customers have programmed FT232R/FT245R devices
+	 * with an endpoint size of 0 - not good.  In this case, we
+	 * want to override the endpoint descriptor setting and use a
+	 * value of 64 for wMaxPacketSize */
+	for (i = 0; i < num_endpoints; i++) {
+		dev_info(&udev->dev, "Endpoint %d MaxPacketSize %d\n", i+1,
+			interface->cur_altsetting->endpoint[i].desc.wMaxPacketSize);
+		ep_desc = &interface->cur_altsetting->endpoint[i].desc;
+		if (ep_desc->wMaxPacketSize == 0) {
+			ep_desc->wMaxPacketSize = cpu_to_le16(0x40);
+			dev_info(&udev->dev, "Overriding wMaxPacketSize on endpoint %d\n", i);
+		}
+	}
+
+	/* set max packet size based on descriptor */
+	priv->max_packet_size = ep_desc->wMaxPacketSize;
+
+	dev_info(&udev->dev, "Setting MaxPacketSize %d\n", priv->max_packet_size);
+}
+
+
 /*
  * ***************************************************************************
  * Sysfs Attribute
@@ -1485,6 +1524,7 @@
 	usb_set_serial_port_data(port, priv);
 
 	ftdi_determine_type(port);
+	ftdi_set_max_packet_size(port);
 	read_latency_timer(port);
 	create_sysfs_attrs(port);
 	return 0;
@@ -1740,8 +1780,8 @@
 	if (data_offset > 0) {
 		/* Original sio needs control bytes too... */
 		transfer_size += (data_offset *
-				((count + (PKTSZ - 1 - data_offset)) /
-				 (PKTSZ - data_offset)));
+				((count + (priv->max_packet_size - 1 - data_offset)) /
+				 (priv->max_packet_size - data_offset)));
 	}
 
 	buffer = kmalloc(transfer_size, GFP_ATOMIC);
@@ -1763,7 +1803,7 @@
 	if (data_offset > 0) {
 		/* Original sio requires control byte at start of
 		   each packet. */
-		int user_pktsz = PKTSZ - data_offset;
+		int user_pktsz = priv->max_packet_size - data_offset;
 		int todo = count;
 		unsigned char *first_byte = buffer;
 		const unsigned char *current_position = buf;
@@ -1859,7 +1899,7 @@
 	data_offset = priv->write_offset;
 	if (data_offset > 0) {
 		/* Subtract the control bytes */
-		countback -= (data_offset * DIV_ROUND_UP(countback, PKTSZ));
+		countback -= (data_offset * DIV_ROUND_UP(countback, priv->max_packet_size));
 	}
 	spin_lock_irqsave(&priv->tx_lock, flags);
 	--priv->tx_outstanding_urbs;
@@ -1961,7 +2001,7 @@
 
 	/* count data bytes, but not status bytes */
 	countread = urb->actual_length;
-	countread -= 2 * DIV_ROUND_UP(countread, PKTSZ);
+	countread -= 2 * DIV_ROUND_UP(countread, priv->max_packet_size);
 	spin_lock_irqsave(&priv->rx_lock, flags);
 	priv->rx_bytes += countread;
 	spin_unlock_irqrestore(&priv->rx_lock, flags);
@@ -2034,7 +2074,7 @@
 
 	need_flip = 0;
 	for (packet_offset = priv->rx_processed;
-		packet_offset < urb->actual_length; packet_offset += PKTSZ) {
+		packet_offset < urb->actual_length; packet_offset += priv->max_packet_size) {
 		int length;
 
 		/* Compare new line status to the old one, signal if different/
@@ -2049,7 +2089,7 @@
 			priv->prev_status = new_status;
 		}
 
-		length = min_t(u32, PKTSZ, urb->actual_length-packet_offset)-2;
+		length = min_t(u32, priv->max_packet_size, urb->actual_length-packet_offset)-2;
 		if (length < 0) {
 			dev_err(&port->dev, "%s - bad packet length: %d\n",
 				__func__, length+2);