From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755826AbaHVEjc (ORCPT ); Fri, 22 Aug 2014 00:39:32 -0400 Received: from shards.monkeyblade.net ([149.20.54.216]:46241 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750898AbaHVEja (ORCPT ); Fri, 22 Aug 2014 00:39:30 -0400 Date: Thu, 21 Aug 2014 21:39:29 -0700 (PDT) Message-Id: <20140821.213929.2048600939729474726.davem@davemloft.net> To: jonas.jensen@gmail.com Cc: netdev@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, f.fainelli@gmail.com, eric.dumazet@gmail.com Subject: Re: [PATCH v5 1/2] net: moxa: clear TX descriptor length bits From: David Miller 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> X-Mailer: Mew version 6.5 on Emacs 24.1 / Mule 6.0 (HANACHIRUSATO) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.7 (shards.monkeyblade.net [149.20.54.216]); Thu, 21 Aug 2014 21:39:30 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jonas Jensen Date: Wed, 20 Aug 2014 16:18:42 +0200 > @@ -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); Like others I wonder why the existing descriptor value is being read at all. It's inefficient and completely unnecessary, you can just compute a new value from scratch, and that way all of these "uncleared field" issues just automatically disappear.