net: ravb: Disable IP header RX checksum offloading

For IPv4 packets, the header checksum will always be checked in software
in the RX path (inet_gro_receive() calls ip_fast_csum() unconditionally)
so there is no advantage in asking the hardware to also calculate this
checksum.

Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Signed-off-by: Paul Barker <paul.barker.ct@bp.renesas.com>
Signed-off-by: Andrew Lunn <andrew@lunn.ch>

diff --git a/drivers/net/ethernet/renesas/ravb.h b/drivers/net/ethernet/renesas/ravb.h
index 4e1e0a754cd93acc0ddf269bf201bbb777a00a0d..98496aa39f3d9876fc43fc690b38eee8cb1e4fe5 100644 (file)
--- a/drivers/net/ethernet/renesas/ravb.h
+++ b/drivers/net/ethernet/renesas/ravb.h
@@ -1014,7 +1014,7 @@ enum CSR2_BIT {
        CSR2_RDHD       = 0x08000000,
 };
 
-#define CSR2_CSUM_ENABLE (CSR2_RIP4 | CSR2_RTCP4 | CSR2_RUDP4 | CSR2_RICMP4)
+#define CSR2_CSUM_ENABLE (CSR2_RTCP4 | CSR2_RUDP4 | CSR2_RICMP4)
 
 #define DBAT_ENTRY_NUM 22
 #define RX_QUEUE_OFFSET        4

diff --git a/drivers/net/ethernet/renesas/ravb_main.c b/drivers/net/ethernet/renesas/ravb_main.c
index c8988c0c85a16dc81e17f33f96b70417147f9586..43db69d03684edb34641e12ecc91708da0801d1b 100644 (file)
--- a/drivers/net/ethernet/renesas/ravb_main.c
+++ b/drivers/net/ethernet/renesas/ravb_main.c
@@ -749,13 +749,18 @@ static void ravb_get_tx_tstamp(struct net_device *ndev)
 static void ravb_rx_csum_gbeth(struct sk_buff *skb)
 {
        struct skb_shared_info *shinfo = skb_shinfo(skb);
-       __wsum csum_ip_hdr, csum_proto;
+       __wsum csum_proto;
        skb_frag_t *last_frag;
        u8 *hw_csum;
 
        /* The hardware checksum status is contained in sizeof(__sum16) * 2 = 4
-        * bytes appended to packet data. First 2 bytes is ip header checksum
-        * and last 2 bytes is protocol checksum.
+        * bytes appended to packet data.
+        *
+        * For ipv4, the first 2 bytes are the ip header checksum status. We can
+        * ignore this as it will always be re-checked in inet_gro_receive().
+        *
+        * The last 2 bytes are the protocol checksum status which will be zero
+        * if the checksum has been validated.
         */
        if (unlikely(skb->len < sizeof(__sum16) * 2))
                return;
@@ -771,16 +776,13 @@ static void ravb_rx_csum_gbeth(struct sk_buff *skb)
        hw_csum -= sizeof(__sum16);
        csum_proto = csum_unfold((__force __sum16)get_unaligned_le16(hw_csum));
 
-       hw_csum -= sizeof(__sum16);
-       csum_ip_hdr = csum_unfold((__force __sum16)get_unaligned_le16(hw_csum));
-
        if (skb_is_nonlinear(skb))
                skb_frag_size_sub(last_frag, 2 * sizeof(__sum16));
        else
                skb_trim(skb, skb->len - 2 * sizeof(__sum16));
 
        /* TODO: IPV6 Rx checksum */
-       if (skb->protocol == htons(ETH_P_IP) && !csum_ip_hdr && !csum_proto)
+       if (skb->protocol == htons(ETH_P_IP) && !csum_proto)
                skb->ip_summed = CHECKSUM_UNNECESSARY;
 }