cns3xxx: ethernet - clean up tx descs only when needed

We already clean up tx descriptors in the napi eth_poll() function so it
would likely be rare to run out of available descriptors in eth_xmit. Thus
we can clean them up only when needed and return busy only when we
still don't have enough.

Signed-off-by: Tim Harvey <tharvey@gateworks.com>
SVN-Revision: 39762

diff --git a/target/linux/cns3xxx/files/drivers/net/ethernet/cavium/cns3xxx_eth.c b/target/linux/cns3xxx/files/drivers/net/ethernet/cavium/cns3xxx_eth.c
index bbbbf5c09160cbc63a9d65e14b75e1a8cba691e9..9692d4799409ff0a7fa5972d376c475fd06a5b50 100644 (file)
--- a/target/linux/cns3xxx/files/drivers/net/ethernet/cavium/cns3xxx_eth.c
+++ b/target/linux/cns3xxx/files/drivers/net/ethernet/cavium/cns3xxx_eth.c
@@ -583,7 +583,7 @@ static void eth_check_num_used(struct _tx_ring *tx_ring)
        }
 }
 
-static void eth_complete_tx(struct sw *sw)
+static int eth_complete_tx(struct sw *sw)
 {
        struct _tx_ring *tx_ring = &sw->tx_ring;
        struct tx_desc *desc;
@@ -615,6 +615,8 @@ static void eth_complete_tx(struct sw *sw)
        tx_ring->free_index = index;
        tx_ring->num_used -= i;
        eth_check_num_used(tx_ring);
+
+       return TX_DESCS - tx_ring->num_used;
 }
 
 static int eth_poll(struct napi_struct *napi, int budget)
@@ -776,11 +778,13 @@ static int eth_xmit(struct sk_buff *skb, struct net_device *dev)
        skb_walk_frags(skb, skb1)
                nr_desc++;
 
-       eth_schedule_poll(sw);
        spin_lock_bh(&tx_lock);
        if ((tx_ring->num_used + nr_desc + 1) >= TX_DESCS) {
-               spin_unlock_bh(&tx_lock);
-               return NETDEV_TX_BUSY;
+               /* clean up tx descriptors when needed */
+               if (eth_complete_tx(sw) < nr_desc) {
+                       spin_unlock_bh(&tx_lock);
+                       return NETDEV_TX_BUSY;
+               }
        }
 
        index = index0 = tx_ring->cur_index;