From patchwork Tue Mar 4 10:32:33 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Simon Kagstrom X-Patchwork-Id: 3760861 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 A18469F376 for ; Tue, 4 Mar 2014 10:33:20 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id D1E542039E for ; Tue, 4 Mar 2014 10:33:19 +0000 (UTC) Received: from casper.infradead.org (casper.infradead.org [85.118.1.10]) (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 A5631200DB for ; Tue, 4 Mar 2014 10:33:17 +0000 (UTC) Received: from merlin.infradead.org ([2001:4978:20e::2]) by casper.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1WKmer-0005Ml-2x; Tue, 04 Mar 2014 10:33:09 +0000 Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1WKmeo-000749-QT; Tue, 04 Mar 2014 10:33:06 +0000 Received: from ernst.netinsight.se ([194.16.221.21]) by merlin.infradead.org with smtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1WKmel-00073i-9e for linux-arm-kernel@lists.infradead.org; Tue, 04 Mar 2014 10:33:04 +0000 Received: from marrow.netinsight.se (unverified [10.100.3.78]) by ernst.netinsight.se (EMWAC SMTPRS 0.83) with SMTP id ; Tue, 04 Mar 2014 11:32:33 +0100 Date: Tue, 4 Mar 2014 11:32:33 +0100 From: Simon =?UTF-8?B?S8OlZ3N0csO2bQ==?= To: linux-arm-kernel@lists.infradead.org Subject: BUG_ON for DMA-bounce and bidirectional mappings (e100 on IXP4xx) Message-ID: <20140304113233.14c95fe0@marrow.netinsight.se> X-Mailer: Claws Mail 3.9.3 (GTK+ 2.24.10; x86_64-pc-linux-gnu) MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20140304_053303_586088_8EA9D886 X-CRM114-Status: UNSURE ( 6.99 ) X-CRM114-Notice: Please train this message. X-Spam-Score: -2.6 (--) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.15 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=-4.2 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, 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 (Sorry, sent to wrong mailing list address) Hi! We have a IXP4xx-based board which has an e100 NIC. During bootup, we trigger a BUG_ON in dmabounce.c because the mapped direction doesn't match the synced one. e100.c maps buffers bidirectional, but the sync is done fromdevice. Krzysztof Ha?asa sent a patch 2012-09-20 which excludes bidirectional mappings from the sync BUG_ONs, as seen below. We need that patch for our board to boot. The patch in full is available at http://patchwork.ozlabs.org/patch/185486/ This was never applied, but also received no comments. Does the patch make sense? For further reference, the e100 BUG_ON was discussed here a few years ago: http://comments.gmane.org/gmane.linux.ports.arm.kernel/48922 there is a e100 patch there from Jesse Brandeburg which changes the mapping, however with that patch the NIC stops receiving traffic after a while. Thanks, // Simon --- a/arch/arm/common/dmabounce.c +++ b/arch/arm/common/dmabounce.c @@ -375,7 +375,7 @@ static int __dmabounce_sync_for_cpu(struct device *dev, dma_addr_t addr, off = addr - buf->safe_dma_addr; - BUG_ON(buf->direction != dir); + BUG_ON(buf->direction != dir && buf->direction != DMA_BIDIRECTIONAL); dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x off=%#lx) mapped to %p (dma=%#x)\n", __func__, buf->ptr, virt_to_dma(dev, buf->ptr), off, @@ -415,7 +415,7 @@ static int __dmabounce_sync_for_device(struct device *dev, dma_addr_t addr, off = addr - buf->safe_dma_addr; - BUG_ON(buf->direction != dir); + BUG_ON(buf->direction != dir && buf->direction != DMA_BIDIRECTIONAL); dev_dbg(dev, "%s: unsafe buffer %p (dma=%#x off=%#lx) mapped to %p (dma=%#x)\n", __func__, buf->ptr, virt_to_dma(dev, buf->ptr), off,