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authorDaniel Hellstrom <daniel@gaisler.com>2011-01-14 03:02:39 +0000
committerDavid S. Miller <davem@davemloft.net>2011-01-14 12:45:53 -0800
commit2a2bc012b98729ce9a39386faed28d11ee021683 (patch)
tree0f7de3c1caf167444abfe9f6f449759f94a094d4
parentbbe9e637330abe55442aebe799425e224086959f (diff)
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GRETH: GBit transmit descriptor handling optimization
It is safe to enable all fragments before enabling the first descriptor, this way all descriptors don't have to be processed twice, added extra memory barrier. Signed-off-by: Daniel Hellstrom <daniel@gaisler.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--drivers/net/greth.c19
1 files changed, 10 insertions, 9 deletions
diff --git a/drivers/net/greth.c b/drivers/net/greth.c
index b307696..869e38d 100644
--- a/drivers/net/greth.c
+++ b/drivers/net/greth.c
@@ -503,7 +503,7 @@ greth_start_xmit_gbit(struct sk_buff *skb, struct net_device *dev)
greth->tx_skbuff[curr_tx] = NULL;
bdp = greth->tx_bd_base + curr_tx;
- status = GRETH_TXBD_CSALL;
+ status = GRETH_TXBD_CSALL | GRETH_BD_EN;
status |= frag->size & GRETH_BD_LEN;
/* Wrap around descriptor ring */
@@ -540,26 +540,27 @@ greth_start_xmit_gbit(struct sk_buff *skb, struct net_device *dev)
wmb();
- /* Enable the descriptors that we configured ... */
- for (i = 0; i < nr_frags + 1; i++) {
- bdp = greth->tx_bd_base + greth->tx_next;
- greth_write_bd(&bdp->stat, greth_read_bd(&bdp->stat) | GRETH_BD_EN);
- greth->tx_next = NEXT_TX(greth->tx_next);
- greth->tx_free--;
- }
+ /* Enable the descriptor chain by enabling the first descriptor */
+ bdp = greth->tx_bd_base + greth->tx_next;
+ greth_write_bd(&bdp->stat, greth_read_bd(&bdp->stat) | GRETH_BD_EN);
+ greth->tx_next = curr_tx;
+ greth->tx_free -= nr_frags + 1;
+
+ wmb();
greth_enable_tx(greth);
return NETDEV_TX_OK;
frag_map_error:
- /* Unmap SKB mappings that succeeded */
+ /* Unmap SKB mappings that succeeded and disable descriptor */
for (i = 0; greth->tx_next + i != curr_tx; i++) {
bdp = greth->tx_bd_base + greth->tx_next + i;
dma_unmap_single(greth->dev,
greth_read_bd(&bdp->addr),
greth_read_bd(&bdp->stat) & GRETH_BD_LEN,
DMA_TO_DEVICE);
+ greth_write_bd(&bdp->stat, 0);
}
map_error:
if (net_ratelimit())