enc28j60: Fix sporadic packet loss (corrected again)

Submitted by Baruch Siach on Dec. 2, 2008, 3:07 p.m.

Details

Message ID 20081202150700.GF24490@diamond.tkos.co.il
State Accepted
Delegated to: David Miller
Headers show

Commit Message

Baruch Siach Dec. 2, 2008, 3:07 p.m.
Packet data read from the RX buffer the when the RSV is at the end of the RX 
buffer does not warp around. This causes packet loss, as the actual data is 
never read. Fix this by calculating the right packet data location.

Thanks to Shachar Shemesh for suggesting the fix.

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Acked-by: Claudio Lanconelli <lanconelli.claudio@eptar.com>

---

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--- drivers/net/enc28j60.c-git	2008-12-02 14:30:10.000000000 +0200
+++ drivers/net/enc28j60.c	2008-12-02 14:41:51.000000000 +0200
@@ -568,6 +568,17 @@  static u16 erxrdpt_workaround(u16 next_p
 	return erxrdpt;
 }
 
+/*
+ * Calculate wrap around when reading beyond the end of the RX buffer
+ */
+static u16 rx_packet_start(u16 ptr)
+{
+	if (ptr + RSV_SIZE > RXEND_INIT)
+		return (ptr + RSV_SIZE) - (RXEND_INIT - RXSTART_INIT + 1);
+	else
+		return ptr + RSV_SIZE;
+}
+
 static void nolock_rxfifo_init(struct enc28j60_net *priv, u16 start, u16 end)
 {
 	u16 erxrdpt;
@@ -938,8 +949,9 @@  static void enc28j60_hw_rx(struct net_de
 			skb->dev = ndev;
 			skb_reserve(skb, NET_IP_ALIGN);
 			/* copy the packet from the receive buffer */
-			enc28j60_mem_read(priv, priv->next_pk_ptr + sizeof(rsv),
-					len, skb_put(skb, len));
+			enc28j60_mem_read(priv,
+				rx_packet_start(priv->next_pk_ptr),
+				len, skb_put(skb, len));
 			if (netif_msg_pktdata(priv))
 				dump_packet(__func__, skb->len, skb->data);
 			skb->protocol = eth_type_trans(skb, ndev);