From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752613AbaHTRKP (ORCPT ); Wed, 20 Aug 2014 13:10:15 -0400 Received: from mail-ie0-f181.google.com ([209.85.223.181]:55910 "EHLO mail-ie0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751419AbaHTRKN (ORCPT ); Wed, 20 Aug 2014 13:10:13 -0400 Message-ID: <1408554610.5604.11.camel@edumazet-glaptop2.roam.corp.google.com> Subject: Re: [PATCH v5 1/2] net: moxa: clear TX descriptor length bits From: Eric Dumazet To: Jonas Jensen Cc: netdev@vger.kernel.org, davem@davemloft.net, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, f.fainelli@gmail.com Date: Wed, 20 Aug 2014 10:10:10 -0700 In-Reply-To: <1408544322-32023-1-git-send-email-jonas.jensen@gmail.com> References: <1408459784-9385-1-git-send-email-jonas.jensen@gmail.com> <1408544322-32023-1-git-send-email-jonas.jensen@gmail.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3-0ubuntu6 Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2014-08-20 at 16:18 +0200, Jonas Jensen wrote: > TX buffer length is not cleared on ndo_start_xmit(). > Failing to do so can bug/hang the controller and > cause TX interrupts to stop altogether. > > diff --git a/drivers/net/ethernet/moxa/moxart_ether.c b/drivers/net/ethernet/moxa/moxart_ether.c > index 5020fd4..aa45607 100644 > --- a/drivers/net/ethernet/moxa/moxart_ether.c > +++ b/drivers/net/ethernet/moxa/moxart_ether.c > @@ -348,7 +348,8 @@ static int moxart_mac_start_xmit(struct sk_buff *skb, struct net_device *ndev) > > txdes1 = readl(desc + TX_REG_OFFSET_DESC1); > txdes1 |= TX_DESC1_LTS | TX_DESC1_FTS; > - txdes1 &= ~(TX_DESC1_FIFO_COMPLETE | TX_DESC1_INTR_COMPLETE); > + txdes1 &= ~(TX_DESC1_FIFO_COMPLETE | TX_DESC1_INTR_COMPLETE | > + TX_DESC1_BUF_SIZE_MASK); > txdes1 |= (len & TX_DESC1_BUF_SIZE_MASK); > writel(txdes1, desc + TX_REG_OFFSET_DESC1); > writel(TX_DESC0_DMA_OWN, desc + TX_REG_OFFSET_DESC0); Wouldnt it be faster to not use readl() at all here ? readl() is only used to get TX_DESC1_END bit. It seems you could replace the thing by : txdes1 = TX_DESC1_LTS | TX_DESC1_FTS | (len & TX_DESC1_BUF_SIZE_MASK); if (tx_head == TX_DESC_NUM_MASK) txdes1 |= TX_DESC1_END; From mboxrd@z Thu Jan 1 00:00:00 1970 From: eric.dumazet@gmail.com (Eric Dumazet) Date: Wed, 20 Aug 2014 10:10:10 -0700 Subject: [PATCH v5 1/2] net: moxa: clear TX descriptor length bits In-Reply-To: <1408544322-32023-1-git-send-email-jonas.jensen@gmail.com> References: <1408459784-9385-1-git-send-email-jonas.jensen@gmail.com> <1408544322-32023-1-git-send-email-jonas.jensen@gmail.com> Message-ID: <1408554610.5604.11.camel@edumazet-glaptop2.roam.corp.google.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wed, 2014-08-20 at 16:18 +0200, Jonas Jensen wrote: > TX buffer length is not cleared on ndo_start_xmit(). > Failing to do so can bug/hang the controller and > cause TX interrupts to stop altogether. > > diff --git a/drivers/net/ethernet/moxa/moxart_ether.c b/drivers/net/ethernet/moxa/moxart_ether.c > index 5020fd4..aa45607 100644 > --- a/drivers/net/ethernet/moxa/moxart_ether.c > +++ b/drivers/net/ethernet/moxa/moxart_ether.c > @@ -348,7 +348,8 @@ static int moxart_mac_start_xmit(struct sk_buff *skb, struct net_device *ndev) > > txdes1 = readl(desc + TX_REG_OFFSET_DESC1); > txdes1 |= TX_DESC1_LTS | TX_DESC1_FTS; > - txdes1 &= ~(TX_DESC1_FIFO_COMPLETE | TX_DESC1_INTR_COMPLETE); > + txdes1 &= ~(TX_DESC1_FIFO_COMPLETE | TX_DESC1_INTR_COMPLETE | > + TX_DESC1_BUF_SIZE_MASK); > txdes1 |= (len & TX_DESC1_BUF_SIZE_MASK); > writel(txdes1, desc + TX_REG_OFFSET_DESC1); > writel(TX_DESC0_DMA_OWN, desc + TX_REG_OFFSET_DESC0); Wouldnt it be faster to not use readl() at all here ? readl() is only used to get TX_DESC1_END bit. It seems you could replace the thing by : txdes1 = TX_DESC1_LTS | TX_DESC1_FTS | (len & TX_DESC1_BUF_SIZE_MASK); if (tx_head == TX_DESC_NUM_MASK) txdes1 |= TX_DESC1_END;