ar5523_rx_desc
struct ar5523_rx_desc *desc;
desc = (struct ar5523_rx_desc *)
(data->skb->data + usblen - sizeof(struct ar5523_rx_desc));
skb_put(data->skb, rxlen - sizeof(struct ar5523_rx_desc));
sizeof(struct ar5523_rx_desc)) + 3) & ~3)