From patchwork Fri Jan 14 13:02:39 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Hellstrom X-Patchwork-Id: 78893 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id CC9AFB70D5 for ; Sat, 15 Jan 2011 00:03:23 +1100 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757450Ab1ANNDB (ORCPT ); Fri, 14 Jan 2011 08:03:01 -0500 Received: from mail175c2.megamailservers.com ([69.49.111.75]:57038 "EHLO mail175c2.megamailservers.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756925Ab1ANNCz (ORCPT ); Fri, 14 Jan 2011 08:02:55 -0500 X-POP-User: sandi@gaisler.com Received: from localhost.localdomain (static-92-33-28-242.sme.bredbandsbolaget.se [92.33.28.242]) by mail175c2.megamailservers.com (8.13.6/8.13.1) with ESMTP id p0ED2mBp016470; Fri, 14 Jan 2011 08:02:51 -0500 From: Daniel Hellstrom To: davem@davemloft.net Cc: netdev@vger.kernel.org, kristoffer@gaisler.com Subject: [PATCH 3/7 v2] GRETH: GBit transmit descriptor handling optimization Date: Fri, 14 Jan 2011 14:02:39 +0100 Message-Id: <1295010163-2585-3-git-send-email-daniel@gaisler.com> X-Mailer: git-send-email 1.5.4 In-Reply-To: <1295010163-2585-1-git-send-email-daniel@gaisler.com> References: <1295010163-2585-1-git-send-email-daniel@gaisler.com> X-CSC: 0 X-CHA: v=1.1 cv=0J/+zcfpZqnYLmiDeyIFo++f7xpDbu+58lrGJvU/+0Q= c=1 sm=1 a=6I2E3G-k2nwA:10 a=jXKJviUpWSOlMmIvGrHOfw==:17 a=ebG-ZW-8AAAA:8 a=XfHqL3PBNBSqhD3tT5IA:9 a=1XTv_qugbB_pmwOG0V4il4Uwut8A:4 a=cCYF7-FHeg4A:10 a=jXKJviUpWSOlMmIvGrHOfw==:117 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org 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 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())