From 2a2bc012b98729ce9a39386faed28d11ee021683 Mon Sep 17 00:00:00 2001 From: Daniel Hellstrom Date: Fri, 14 Jan 2011 03:02:39 +0000 Subject: [PATCH] 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 Signed-off-by: David S. Miller --- drivers/net/greth.c | 19 ++++++++++--------- 1 file changed, 10 insertions(+), 9 deletions(-) diff --git a/drivers/net/greth.c b/drivers/net/greth.c index b307696e0f63..869e38d6f41b 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())