skge: increase TX threshold for Jumbo

Need to increase TX threshold when doing Jumbo frames on dual port board
to avoid underruns. (Code from sk98lin).
Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

drivers/net/skge.c

@@ -1633,15 +1633,14 @@ static void genesis_mac_init(struct skge_hw *hw, int port)
 	}
 	xm_write16(hw, port, XM_RX_CMD, r);
 
-
 	/* We want short frames padded to 60 bytes. */
 	xm_write16(hw, port, XM_TX_CMD, XM_TX_AUTO_PAD);
 
-	/*
-	 * Bump up the transmit threshold. This helps hold off transmit
-	 * underruns when we're blasting traffic from both ports at once.
-	 */
-	xm_write16(hw, port, XM_TX_THR, 512);
+	/* Increase threshold for jumbo frames on dual port */
+	if (hw->ports > 1 && jumbo)
+		xm_write16(hw, port, XM_TX_THR, 1020);
+	else
+		xm_write16(hw, port, XM_TX_THR, 512);
 
 	/*
 	 * Enable the reception of all error frames. This is is