ar71xx: fix up alignment handling

- on ar724x, rx buffers can be aligned with an offset of 2, which keeps the ip header aligned
- alignment offset is only added if the ar8216 workaround is not active and the phy driver does not advertise its own packet alignment
- ar71xx and ar91xx can not handle rx alignment offsets, however taking a hit on unaligned exceptions seems to have less overhead than re-aligning the data for large packets
- use memmove to re-align small packets, if necessary

tested on ar9132, ar7240 and ar7242 based devices without ar8216 headers

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@20892 3c298f89-4303-0410-b956-a3cf2f4a3e73

diff --git a/target/linux/ar71xx/files/drivers/net/ag71xx/ag71xx_ar8216.c b/target/linux/ar71xx/files/drivers/net/ag71xx/ag71xx_ar8216.c
index 7801b9f..7ec43b7 100644 (file)
--- a/target/linux/ar71xx/files/drivers/net/ag71xx/ag71xx_ar8216.c
+++ b/target/linux/ar71xx/files/drivers/net/ag71xx/ag71xx_ar8216.c
@@ -39,7 +39,6 @@ int ag71xx_remove_ar8216_header(struct ag71xx *ag, struct sk_buff *skb,
                return -EINVAL;
        }
 
-       skb_put(skb, pktlen);
        skb_pull(skb, AR8216_HEADER_LEN);
        return 0;
 }

diff --git a/target/linux/ar71xx/files/drivers/net/ag71xx/ag71xx_main.c b/target/linux/ar71xx/files/drivers/net/ag71xx/ag71xx_main.c
index 8d61294..a3b5f95 100644 (file)
--- a/target/linux/ar71xx/files/drivers/net/ag71xx/ag71xx_main.c
+++ b/target/linux/ar71xx/files/drivers/net/ag71xx/ag71xx_main.c
@@ -192,9 +192,28 @@ static void ag71xx_ring_rx_clean(struct ag71xx *ag)
                }
 }
 
+static int ag71xx_rx_reserve(struct ag71xx *ag)
+{
+       int reserve = 0;
+
+       if (ag71xx_get_pdata(ag)->is_ar724x) {
+               if (!ag71xx_has_ar8216(ag))
+                       reserve = 2;
+
+               if (ag->phy_dev)
+                       reserve += 4 - (ag->phy_dev->pkt_align % 4);
+
+               reserve %= 4;
+       }
+
+       return reserve + AG71XX_RX_PKT_RESERVE;
+}
+
+
 static int ag71xx_ring_rx_init(struct ag71xx *ag)
 {
        struct ag71xx_ring *ring = &ag->rx_ring;
+       unsigned int reserve = ag71xx_rx_reserve(ag);
        unsigned int i;
        int ret;
 
@@ -212,14 +231,14 @@ static int ag71xx_ring_rx_init(struct ag71xx *ag)
                struct sk_buff *skb;
                dma_addr_t dma_addr;
 
-               skb = dev_alloc_skb(AG71XX_RX_PKT_SIZE + AG71XX_RX_PKT_RESERVE);
+               skb = dev_alloc_skb(AG71XX_RX_PKT_SIZE + reserve);
                if (!skb) {
                        ret = -ENOMEM;
                        break;
                }
 
                skb->dev = ag->dev;
-               skb_reserve(skb, AG71XX_RX_PKT_RESERVE);
+               skb_reserve(skb, reserve);
 
                dma_addr = dma_map_single(&ag->dev->dev, skb->data,
                                          AG71XX_RX_PKT_SIZE,
@@ -242,6 +261,7 @@ static int ag71xx_ring_rx_init(struct ag71xx *ag)
 static int ag71xx_ring_rx_refill(struct ag71xx *ag)
 {
        struct ag71xx_ring *ring = &ag->rx_ring;
+       unsigned int reserve = ag71xx_rx_reserve(ag);
        unsigned int count;
 
        count = 0;
@@ -254,12 +274,11 @@ static int ag71xx_ring_rx_refill(struct ag71xx *ag)
                        dma_addr_t dma_addr;
                        struct sk_buff *skb;
 
-                       skb = dev_alloc_skb(AG71XX_RX_PKT_SIZE +
-                                           AG71XX_RX_PKT_RESERVE);
+                       skb = dev_alloc_skb(AG71XX_RX_PKT_SIZE + reserve);
                        if (skb == NULL)
                                break;
 
-                       skb_reserve(skb, AG71XX_RX_PKT_RESERVE);
+                       skb_reserve(skb, reserve);
                        skb->dev = ag->dev;
 
                        dma_addr = dma_map_single(&ag->dev->dev, skb->data,
@@ -759,30 +778,26 @@ static int ag71xx_tx_packets(struct ag71xx *ag)
        return sent;
 }
 
-static int ag71xx_rx_copy_skb(struct ag71xx *ag, struct sk_buff **pskb,
-                             int pktlen)
+static void ag71xx_rx_align_skb(struct ag71xx *ag, struct sk_buff *skb, int len)
 {
-       struct sk_buff *copy_skb;
+       int offset = ((unsigned long) skb->data) % 4;
+       void *data;
 
-       if (ag->phy_dev && (ag->phy_dev->pkt_align % 4) == 2)
-               goto keep;
-
-       copy_skb = netdev_alloc_skb(ag->dev, pktlen + NET_IP_ALIGN);
-       if (!copy_skb)
-               return -ENOMEM;
+       if (offset == 2)
+               return;
 
-       skb_reserve(copy_skb, NET_IP_ALIGN);
-       skb_copy_from_linear_data(*pskb, copy_skb->data, pktlen);
-       skb_put(copy_skb, pktlen);
+       if (ag->phy_dev && ag->phy_dev->pkt_align != 0)
+               return;
 
-       dev_kfree_skb_any(*pskb);
-       *pskb = copy_skb;
+       if (len > 128)
+               return;
 
-       return 0;
+       if (WARN_ON(skb_headroom(skb) < 2))
+               return;
 
- keep:
-       skb_put(*pskb, pktlen);
-       return 0;
+       data = skb->data;
+       skb->data -= 2;
+       memmove(skb->data, data, len);
 }
 
 static int ag71xx_rx_packets(struct ag71xx *ag, int limit)
@@ -822,10 +837,11 @@ static int ag71xx_rx_packets(struct ag71xx *ag, int limit)
                dev->stats.rx_packets++;
                dev->stats.rx_bytes += pktlen;
 
+               skb_put(skb, pktlen);
                if (ag71xx_has_ar8216(ag))
                        err = ag71xx_remove_ar8216_header(ag, skb, pktlen);
-               else
-                       err = ag71xx_rx_copy_skb(ag, &skb, pktlen);
+
+               ag71xx_rx_align_skb(ag, skb, pktlen);
 
                if (err) {
                        dev->stats.rx_dropped++;