net: sh_eth: fix the rxdesc pointer when rx descriptor empty happens

When Receive Descriptor Empty happens, rxdesc pointer of the driver
and actual next descriptor of the controller may be mismatch.
This patch fixes it.

Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/renesas/sh_eth.c

@@ -1101,8 +1101,12 @@ static int sh_eth_rx(struct net_device *ndev)
 
 	/* Restart Rx engine if stopped. */
 	/* If we don't need to check status, don't. -KDU */
-	if (!(sh_eth_read(ndev, EDRRR) & EDRRR_R))
+	if (!(sh_eth_read(ndev, EDRRR) & EDRRR_R)) {
+		/* fix the values for the next receiving */
+		mdp->cur_rx = mdp->dirty_rx = (sh_eth_read(ndev, RDFAR) -
+					       sh_eth_read(ndev, RDLAR)) >> 4;
 		sh_eth_write(ndev, EDRRR_R, EDRRR);
+	}
 
 	return 0;
 }
@@ -1199,8 +1203,6 @@ static void sh_eth_error(struct net_device *ndev, int intr_status)
 		/* Receive Descriptor Empty int */
 		ndev->stats.rx_over_errors++;
 
-		if (sh_eth_read(ndev, EDRRR) ^ EDRRR_R)
-			sh_eth_write(ndev, EDRRR_R, EDRRR);
 		if (netif_msg_rx_err(mdp))
 			dev_err(&ndev->dev, "Receive Descriptor Empty\n");
 	}