From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with SMTP id CD9376B0169 for ; Fri, 29 Jul 2011 06:54:24 -0400 (EDT) Date: Fri, 29 Jul 2011 12:54:22 +0200 From: 'Joerg Roedel' Subject: Re: [RFC] ARM: dma_map|unmap_sg plus iommu Message-ID: <20110729105422.GB13522@8bytes.org> References: <000301cc4dc4$31b53630$951fa290$%szyprowski@samsung.com> <20110729093555.GA13522@8bytes.org> <001901cc4dd8$4afb4e40$e0f1eac0$%szyprowski@samsung.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <001901cc4dd8$4afb4e40$e0f1eac0$%szyprowski@samsung.com> Sender: owner-linux-mm@kvack.org List-ID: To: Marek Szyprowski Cc: "'Ramirez Luna, Omar'" , linux-arm-kernel@lists.infradead.org, linaro-mm-sig@lists.linaro.org, linux-mm@kvack.org, 'Kyungmin Park' , 'Russell King - ARM Linux' , 'Arnd Bergmann' , 'Ohad Ben-Cohen' On Fri, Jul 29, 2011 at 12:14:25PM +0200, Marek Szyprowski wrote: > > This sounds rather hacky. How about partitioning the address space for > > the device and give the dma-api only a part of it. The other parts can > > be directly mapped using the iommu-api then. > > Well, I'm not convinced that iommu-api should be used by the device drivers > directly. If possible we should rather extend dma-mapping than use such hacks. Building this into dma-api would turn it into an iommu-api. The line between the apis are clear. The iommu-api provides direct mapping of bus-addresses to system-addresses while the dma-api puts a memory manager on-top which deals with bus-address allocation itself. So if you want to map bus-addresses directly the iommu-api is the way to go. This is in no way a hack. Regards, Joerg -- 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