From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail6.bemta12.messagelabs.com (mail6.bemta12.messagelabs.com [216.82.250.247]) by kanga.kvack.org (Postfix) with ESMTP id 2C68F6B002D for ; Tue, 11 Oct 2011 14:13:56 -0400 (EDT) From: Krishna Reddy Date: Tue, 11 Oct 2011 11:13:31 -0700 Subject: RE: [Linaro-mm-sig] [PATCH 1/2] ARM: initial proof-of-concept IOMMU mapper for DMA-mapping Message-ID: <401E54CE964CD94BAE1EB4A729C7087E3722519A1F@HQMAIL04.nvidia.com> References: <1314971786-15140-1-git-send-email-m.szyprowski@samsung.com> <1314971786-15140-2-git-send-email-m.szyprowski@samsung.com> <594816116217195c28de13accaf1f9f2.squirrel@www.codeaurora.org> <001f01cc786d$d55222c0$7ff66840$%szyprowski@samsung.com> <401E54CE964CD94BAE1EB4A729C7087E37225197F8@HQMAIL04.nvidia.com> <00b101cc87ee$8976c410$9c644c30$%szyprowski@samsung.com> In-Reply-To: <00b101cc87ee$8976c410$9c644c30$%szyprowski@samsung.com> Content-Language: en-US Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Sender: owner-linux-mm@kvack.org List-ID: To: Marek Szyprowski Cc: "linux-arch@vger.kernel.org" , 'Russell King - ARM Linux' , 'Arnd Bergmann' , 'Joerg Roedel' , "linaro-mm-sig@lists.linaro.org" , "linux-mm@kvack.org" , 'Kyungmin Park' , Andrzej Pietrasiewicz , 'Chunsang Jeong' , "linux-arm-kernel@lists.infradead.org" , 'Laura Abbott' Marek, >It looks that You have simplified arm_iommu_map_sg() function too much.=20 >The main advantage of the iommu is to map scattered memory pages into=20 >contiguous dma address space. DMA-mapping is allowed to merge consecutive >entries in the scatter list if hardware supports that. >http://article.gmane.org/gmane.linux.kernel/1128416 I would update arm_iommu_map_sg() back to coalesce the sg list. >I'm not sure if mmc drivers are aware of coalescing the SG entries togethe= r. >If not the code must be updated to use dma_sg_len() and the dma entries >number returned from dma_map_sg() call. MMC drivers seem to be aware of coalescing the SG entries together as they = are using dma_sg_len(). Let me test and update the patch. -- nvpublic -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org