From patchwork Wed Nov 5 07:58:44 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Aisheng Dong X-Patchwork-Id: 5232931 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork1.web.kernel.org (Postfix) with ESMTP id E17BB9F295 for ; Wed, 5 Nov 2014 09:08:03 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 070692017A for ; Wed, 5 Nov 2014 09:08:03 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 1F6D420173 for ; Wed, 5 Nov 2014 09:08:02 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1XlwXO-0002eV-1E; Wed, 05 Nov 2014 09:05:58 +0000 Received: from mail-by2on0106.outbound.protection.outlook.com ([207.46.100.106] helo=na01-by2-obe.outbound.protection.outlook.com) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1XlwX9-0002BG-GI for linux-arm-kernel@lists.infradead.org; Wed, 05 Nov 2014 09:05:44 +0000 Received: from BN3PR0301CA0007.namprd03.prod.outlook.com (25.160.180.145) by BLUPR03MB327.namprd03.prod.outlook.com (10.141.48.18) with Microsoft SMTP Server (TLS) id 15.1.11.9; Wed, 5 Nov 2014 09:05:18 +0000 Received: from BN1AFFO11FD035.protection.gbl (2a01:111:f400:7c10::181) by BN3PR0301CA0007.outlook.office365.com (2a01:111:e400:4000::17) with Microsoft SMTP Server (TLS) id 15.1.11.14 via Frontend Transport; Wed, 5 Nov 2014 09:05:18 +0000 Received: from tx30smr01.am.freescale.net (192.88.168.50) by BN1AFFO11FD035.mail.protection.outlook.com (10.58.52.159) with Microsoft SMTP Server (TLS) id 15.1.6.13 via Frontend Transport; Wed, 5 Nov 2014 09:05:18 +0000 Received: from shlinux2.ap.freescale.net (shlinux2.ap.freescale.net [10.192.224.44]) by tx30smr01.am.freescale.net (8.14.3/8.14.0) with ESMTP id sA5957Qs031871; Wed, 5 Nov 2014 02:05:15 -0700 From: Dong Aisheng To: Subject: [PATCH V2 2/4] can: m_can: workaround for transmit data less than 4 bytes Date: Wed, 5 Nov 2014 15:58:44 +0800 Message-ID: <1415174326-6623-2-git-send-email-b29396@freescale.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1415174326-6623-1-git-send-email-b29396@freescale.com> References: <1415174326-6623-1-git-send-email-b29396@freescale.com> X-EOPAttributedMessage: 0 X-Forefront-Antispam-Report: CIP:192.88.168.50; CTRY:US; IPV:CAL; IPV:NLI; EFV:NLI; SFV:NSPM; SFS:(10019020)(6009001)(199003)(189002)(54534003)(76176999)(50986999)(229853001)(105606002)(92566001)(31966008)(102836001)(21056001)(64706001)(26826002)(99396003)(47776003)(106466001)(97736003)(95666004)(2351001)(4396001)(20776003)(50226001)(36756003)(107046002)(62966003)(110136001)(46102003)(93916002)(50466002)(88136002)(87936001)(87286001)(19580405001)(48376002)(92726001)(33646002)(44976005)(104166001)(120916001)(77156002)(104016003)(84676001)(6806004)(68736004)(19580395003)(89996001)(42262002); DIR:OUT; SFP:1102; SCL:1; SRVR:BLUPR03MB327; H:tx30smr01.am.freescale.net; FPR:; MLV:ovrnspm; PTR:InfoDomainNonexistent; A:1; MX:1; LANG:en; MIME-Version: 1.0 X-Microsoft-Antispam: UriScan:; X-Microsoft-Antispam: BCL:0;PCL:0;RULEID:;SRVR:BLUPR03MB327; X-Exchange-Antispam-Report-Test: UriScan:; X-Forefront-PRVS: 0386B406AA Received-SPF: Fail (protection.outlook.com: domain of freescale.com does not designate 192.88.168.50 as permitted sender) receiver=protection.outlook.com; client-ip=192.88.168.50; helo=tx30smr01.am.freescale.net; Authentication-Results: spf=fail (sender IP is 192.88.168.50) smtp.mailfrom=Aisheng.Dong@freescale.com; X-OriginatorOrg: freescale.com X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20141105_010543_616347_6333C0C7 X-CRM114-Status: UNSURE ( 8.33 ) X-CRM114-Notice: Please train this message. X-Spam-Score: -0.0 (/) Cc: netdev@vger.kernel.org, varkabhadram@gmail.com, mkl@pengutronix.de, linux-arm-kernel@lists.infradead.org, socketcan@hartkopp.net, b29396@freescale.com, wg@grandegger.com X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-2.5 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_NONE, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP At least on the i.MX6SX with M_CAN IP version 3.0.x, an issue with the Message RAM was discovered. Sending CAN frames with dlc less than 4 bytes will lead to bit errors, when the first 8 bytes of the Message RAM have not been initialized (i.e. written to). To work around this issue, the first 8 bytes are initialized in open() function. Without the workaround, we can easily see the following errors: root@imx6qdlsolo:~# ip link set can0 up type can bitrate 1000000 [ 66.882520] IPv6: ADDRCONF(NETDEV_CHANGE): can0: link becomes ready root@imx6qdlsolo:~# cansend can0 123#112233 [ 66.935640] m_can 20e8000.can can0: Bit Error Uncorrected Signed-off-by: Dong Aisheng --- ChangeLog since v1: * initialize the first 8 bytes of Tx Buffer of Message RAM in open() to workaround the issue --- drivers/net/can/m_can/m_can.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c index 664fe30..f47c200 100644 --- a/drivers/net/can/m_can/m_can.c +++ b/drivers/net/can/m_can/m_can.c @@ -902,6 +902,15 @@ static void m_can_chip_config(struct net_device *dev) /* set bittiming params */ m_can_set_bittiming(dev); + /* At least on the i.MX6SX with M_CAN IP version 3.0.x, an issue with + * the Message RAM was discovered. Sending CAN frames with dlc less + * than 4 bytes will lead to bit errors, when the first 8 bytes of + * the Message RAM have not been initialized (i.e. written to). + * To work around this issue, the first 8 bytes are initialized here. + */ + m_can_fifo_write(priv, 0, M_CAN_FIFO_DATA(0), 0x0); + m_can_fifo_write(priv, 0, M_CAN_FIFO_DATA(1), 0x0); + m_can_config_endisable(priv, false); }