From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935611AbcA1MjW (ORCPT ); Thu, 28 Jan 2016 07:39:22 -0500 Received: from smtp-out4.electric.net ([192.162.216.181]:56439 "EHLO smtp-out4.electric.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934588AbcA1MjS convert rfc822-to-8bit (ORCPT ); Thu, 28 Jan 2016 07:39:18 -0500 From: David Laight To: "'Arnd Bergmann'" , "David S. Miller" CC: "linux-arm-kernel@lists.infradead.org" , "netdev@vger.kernel.org" , =?Windows-1252?Q?fran=E7ois_romieu?= , "linux-kernel@vger.kernel.org" Subject: RE: [PATCH 4/9] net: moxart: use correct accessors for DMA memory Thread-Topic: [PATCH 4/9] net: moxart: use correct accessors for DMA memory Thread-Index: AQHRWQwYRH1kAdypuEmVioYOU+Hr558Q3mmA Date: Thu, 28 Jan 2016 12:36:19 +0000 Message-ID: <063D6719AE5E284EB5DD2968C1650D6D1CCCEDCE@AcuExch.aculab.com> References: <1453903507-3427225-1-git-send-email-arnd@arndb.de> <1453903507-3427225-5-git-send-email-arnd@arndb.de> In-Reply-To: <1453903507-3427225-5-git-send-email-arnd@arndb.de> Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.202.99.200] Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 X-Outbound-IP: 213.249.233.130 X-Env-From: David.Laight@ACULAB.COM X-PolicySMART: 3396946, 3397078 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Arnd Bergmann > Sent: 27 January 2016 14:05 > The moxart ethernet driver confuses coherent DMA buffers with > MMIO registers. > > moxart_ether.c: In function 'moxart_mac_setup_desc_ring': > moxart_ether.c:146:428: error: passing argument 1 of '__fswab32' makes integer from pointer without a > cast [-Werror=int-conversion] > moxart_ether.c:74:39: warning: incorrect type in argument 3 (different address spaces) > moxart_ether.c:74:39: expected void *cpu_addr > moxart_ether.c:74:39: got void [noderef] *tx_desc_base > > This leaves the basic logic alone and uses normal pointers for > the virtual address of the descriptor. As we cannot use readl/writel > to access them, we also introduce our own moxart_desc_read > moxart_desc_write helpers that perform the same endianess swap > as the original code, but without the extra barriers and address > space conversion. I'm pretty sure you need to add some explicit barriers: > @@ -354,8 +364,8 @@ static int moxart_mac_start_xmit(struct sk_buff *skb, struct net_device *ndev) > txdes1 = TX_DESC1_LTS | TX_DESC1_FTS | (len & TX_DESC1_BUF_SIZE_MASK); > if (tx_head == TX_DESC_NUM_MASK) > txdes1 |= TX_DESC1_END; > - writel(txdes1, desc + TX_REG_OFFSET_DESC1); > - writel(TX_DESC0_DMA_OWN, desc + TX_REG_OFFSET_DESC0); > + moxart_desc_write(txdes1, desc + TX_REG_OFFSET_DESC1); > + moxart_desc_write(TX_DESC0_DMA_OWN, desc + TX_REG_OFFSET_DESC0); Those last two writes must happen in that order. There may be others. David