From patchwork Wed Sep 5 08:19:09 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nicolas Ferre X-Patchwork-Id: 1406001 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork1.kernel.org Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) by patchwork1.kernel.org (Postfix) with ESMTP id A879140220 for ; Wed, 5 Sep 2012 08:23:46 +0000 (UTC) Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.76 #1 (Red Hat Linux)) id 1T9AqM-0000sm-Li; Wed, 05 Sep 2012 08:20:14 +0000 Received: from eusmtp01.atmel.com ([212.144.249.243]) by merlin.infradead.org with esmtps (Exim 4.76 #1 (Red Hat Linux)) id 1T9Aq2-0000mz-VL for linux-arm-kernel@lists.infradead.org; Wed, 05 Sep 2012 08:19:56 +0000 Received: from HNOCHT02.corp.atmel.com (10.161.30.162) by eusmtp01.atmel.com (10.161.101.31) with Microsoft SMTP Server (TLS) id 14.2.318.1; Wed, 5 Sep 2012 10:19:31 +0200 Received: from tenerife.rfo.atmel.com (10.161.30.18) by HNOCHT02.corp.atmel.com (10.161.30.162) with Microsoft SMTP Server (TLS) id 14.2.318.1; Wed, 5 Sep 2012 10:19:32 +0200 From: Nicolas Ferre To: Subject: [PATCH 02/10] net/macb: memory barriers cleanup Date: Wed, 5 Sep 2012 10:19:09 +0200 Message-ID: <8f4d7383d051ed4e3617944141c7746505e35638.1346775479.git.nicolas.ferre@atmel.com> X-Mailer: git-send-email 1.7.10 In-Reply-To: References: MIME-Version: 1.0 X-Originating-IP: [10.161.30.18] X-Spam-Note: CRM114 invocation failed X-Spam-Score: -2.1 (--) X-Spam-Report: SpamAssassin version 3.3.2 on merlin.infradead.org summary: Content analysis details: (-2.1 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 SPF_PASS SPF: sender matches SPF record -0.2 RP_MATCHES_RCVD Envelope sender domain matches handover relay domain -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] Cc: patrice.vilchez@atmel.com, nicolas.ferre@atmel.com, linux-kernel@vger.kernel.org, havard@skinnemoen.net, jamie@jamieiles.com, plagnioj@jcrosoft.com, davem@davemloft.net, linux-arm-kernel@lists.infradead.org X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-arm-kernel-bounces@lists.infradead.org Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org From: Havard Skinnemoen Remove a couple of unneeded barriers and document the remaining ones. Signed-off-by: Havard Skinnemoen [nicolas.ferre@atmel.com: split patch in topics] Signed-off-by: Nicolas Ferre --- drivers/net/ethernet/cadence/macb.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) diff --git a/drivers/net/ethernet/cadence/macb.c b/drivers/net/ethernet/cadence/macb.c index 9a10f69..26ca01e 100644 --- a/drivers/net/ethernet/cadence/macb.c +++ b/drivers/net/ethernet/cadence/macb.c @@ -372,7 +372,9 @@ static void macb_tx(struct macb *bp) BUG_ON(skb == NULL); + /* Make hw descriptor updates visible to CPU */ rmb(); + bufstat = bp->tx_ring[tail].ctrl; if (!(bufstat & MACB_BIT(TX_USED))) @@ -415,7 +417,10 @@ static int macb_rx_frame(struct macb *bp, unsigned int first_frag, if (frag == last_frag) break; } + + /* Make descriptor updates visible to hardware */ wmb(); + return 1; } @@ -436,12 +441,14 @@ static int macb_rx_frame(struct macb *bp, unsigned int first_frag, frag_len); offset += RX_BUFFER_SIZE; bp->rx_ring[frag].addr &= ~MACB_BIT(RX_USED); - wmb(); if (frag == last_frag) break; } + /* Make descriptor updates visible to hardware */ + wmb(); + skb->protocol = eth_type_trans(skb, bp->dev); bp->stats.rx_packets++; @@ -461,6 +468,8 @@ static void discard_partial_frame(struct macb *bp, unsigned int begin, for (frag = begin; frag != end; frag = NEXT_RX(frag)) bp->rx_ring[frag].addr &= ~MACB_BIT(RX_USED); + + /* Make descriptor updates visible to hardware */ wmb(); /* @@ -479,7 +488,9 @@ static int macb_rx(struct macb *bp, int budget) for (; budget > 0; tail = NEXT_RX(tail)) { u32 addr, ctrl; + /* Make hw descriptor updates visible to CPU */ rmb(); + addr = bp->rx_ring[tail].addr; ctrl = bp->rx_ring[tail].ctrl; @@ -674,6 +685,8 @@ static int macb_start_xmit(struct sk_buff *skb, struct net_device *dev) bp->tx_ring[entry].addr = mapping; bp->tx_ring[entry].ctrl = ctrl; + + /* Make newly initialized descriptor visible to hardware */ wmb(); entry = NEXT_TX(entry); @@ -782,9 +795,6 @@ static void macb_init_rings(struct macb *bp) static void macb_reset_hw(struct macb *bp) { - /* Make sure we have the write buffer for ourselves */ - wmb(); - /* * Disable RX and TX (XXX: Should we halt the transmission * more gracefully?)