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 888A36B0169 for ; Fri, 29 Jul 2011 05:35:57 -0400 (EDT) Date: Fri, 29 Jul 2011 11:35:55 +0200 From: 'Joerg Roedel' Subject: Re: [RFC] ARM: dma_map|unmap_sg plus iommu Message-ID: <20110729093555.GA13522@8bytes.org> References: <000301cc4dc4$31b53630$951fa290$%szyprowski@samsung.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <000301cc4dc4$31b53630$951fa290$%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 09:50:32AM +0200, Marek Szyprowski wrote: > On Thursday, July 28, 2011 11:10 PM Ramirez Luna, Omar wrote: > > 2. tidspbridge driver sometimes needs to map a physical address into a > > fixed virtual address (i.e. the start of a firmware section is expected to > > be at dsp va 0x20000000), there is no straight forward way to do this with > > the dma api given that it only expects to receive a cpu_addr, a sg or a > > page, by adding iov_address I could pass phys and iov addresses in a sg > > and overcome this limitation, but, these addresses belong to: > > We also encountered the problem of fixed firmware address. We addressed is by > setting io address space start to this address and letting device driver to > rely on the fact that the first call to dma_alloc() will match this address. 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. Regards, Joerg 1 -- 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