From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Hellstrom Subject: [PATCH 06/10] GRETH: GBit transmit descriptor handling optimization Date: Thu, 13 Jan 2011 09:25:31 +0100 Message-ID: <1294907135-24884-6-git-send-email-daniel@gaisler.com> References: <1294907135-24884-1-git-send-email-daniel@gaisler.com> Cc: netdev@vger.kernel.org, kristoffer@gaisler.com To: davem@davemloft.net Return-path: Received: from mail201c2.megamailservers.com ([69.49.111.102]:39241 "EHLO mail201c2.megamailservers.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932808Ab1AMJAL (ORCPT ); Thu, 13 Jan 2011 04:00:11 -0500 In-Reply-To: <1294907135-24884-1-git-send-email-daniel@gaisler.com> Sender: netdev-owner@vger.kernel.org List-ID: 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 --- drivers/net/greth.c | 19 ++++++++++--------- 1 files changed, 10 insertions(+), 9 deletions(-) diff --git a/drivers/net/greth.c b/drivers/net/greth.c index 27578c9..72a4317 100644 --- a/drivers/net/greth.c +++ b/drivers/net/greth.c @@ -513,7 +513,7 @@ 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 */ @@ -550,26 +550,27 @@ 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()) -- 1.5.4