net: fec: clear receive interrupts before processing a packet

[ Upstream commit ed63f1dc ]

The patch just to re-submit the patch "db3421c1" because the
patch "4d494cdc" remove the change.

Clear any pending receive interrupt before we process a pending packet.
This helps to avoid any spurious interrupts being raised after we have
fully cleaned the receive ring, while still allowing an interrupt to be
raised if we receive another packet.

The position of this is critical: we must do this prior to reading the
next packet status to avoid potentially dropping an interrupt when a
packet is still pending.
Acked-by: Fugang Duan <B38611@freescale.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/net/ethernet/freescale/fec_main.c

@@ -1396,6 +1396,7 @@ fec_enet_rx_queue(struct net_device *ndev, int budget, u16 queue_id)
 		if ((status & BD_ENET_RX_LAST) == 0)
 			netdev_err(ndev, "rcv is not +last\n");
 
+		writel(FEC_ENET_RXF, fep->hwp + FEC_IEVENT);
 
 		/* Check for errors. */
 		if (status & (BD_ENET_RX_LG | BD_ENET_RX_SH | BD_ENET_RX_NO |