+static void mv643xx_eth_recalc_skb_size(struct mv643xx_eth_private *mp)
+{
+ int skb_size;
+
+ /*
+ * Reserve 2+14 bytes for an ethernet header (the hardware
+ * automatically prepends 2 bytes of dummy data to each
+ * received packet), 16 bytes for up to four VLAN tags, and
+ * 4 bytes for the trailing FCS -- 36 bytes total.
+ */
+ skb_size = mp->dev->mtu + 36;
+
+ /*
+ * Make sure that the skb size is a multiple of 8 bytes, as
+ * the lower three bits of the receive descriptor's buffer
+ * size field are ignored by the hardware.
+ */
+ mp->skb_size = (skb_size + 7) & ~7;
+}
+