rndis_host: fix transfer size negotiation

This patch should resolve a problem that's troubled support for
some RNDIS peripherals.  It seems to have boiled down to using a
variable to establish transfer size limits before it was assigned,
which caused those devices to fallback to a default "jumbogram"
mode we don't support.  Fix by assigning it earlier for RNDIS.

Signed-off-by: Jean-Christophe Dubois <jcd@tribudubois.net>
[ cleanups ]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

drivers/net/usb/rndis_host.c

@@ -16,10 +16,6 @@
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  */
-
-// #define	DEBUG			// error path messages, extra info
-// #define	VERBOSE			// more; success messages
-
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/netdevice.h>
@@ -318,6 +314,14 @@ generic_rndis_bind(struct usbnet *dev, struct usb_interface *intf, int flags)
 	net->hard_header_len += sizeof (struct rndis_data_hdr);
 	dev->hard_mtu = net->mtu + net->hard_header_len;
 
+	dev->maxpacket = usb_maxpacket(dev->udev, dev->out, 1);
+	if (dev->maxpacket == 0) {
+		if (netif_msg_probe(dev))
+			dev_dbg(&intf->dev, "dev->maxpacket can't be 0\n");
+		retval = -EINVAL;
+		goto fail_and_release;
+	}
+
 	dev->rx_urb_size = dev->hard_mtu + (dev->maxpacket + 1);
 	dev->rx_urb_size &= ~(dev->maxpacket - 1);
 	u.init->max_transfer_size = cpu_to_le32(dev->rx_urb_size);