From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx150.postini.com [74.125.245.150]) by kanga.kvack.org (Postfix) with SMTP id 5D8136B005A for ; Wed, 19 Sep 2012 22:21:43 -0400 (EDT) Message-ID: <505A7DB4.4090902@wwwdotorg.org> Date: Wed, 19 Sep 2012 20:21:40 -0600 From: Stephen Warren MIME-Version: 1.0 Subject: Re: [RFC 0/5] ARM: dma-mapping: New dma_map_ops to control IOVA more precisely References: <1346223335-31455-1-git-send-email-hdoyu@nvidia.com> <20120918124918.GK2505@amd.com> <20120919095843.d1db155e0f085f4fcf64ea32@nvidia.com> <201209190759.46174.arnd@arndb.de> <20120919125020.GQ2505@amd.com> <401E54CE964CD94BAE1EB4A729C7087E379FDC1EEB@HQMAIL04.nvidia.com> In-Reply-To: <401E54CE964CD94BAE1EB4A729C7087E379FDC1EEB@HQMAIL04.nvidia.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Krishna Reddy Cc: Joerg Roedel , Arnd Bergmann , Hiroshi Doyu , "m.szyprowski@samsung.com" , "linux@arm.linux.org.uk" , "minchan@kernel.org" , "chunsang.jeong@linaro.org" , "linux-kernel@vger.kernel.org" , "subashrp@gmail.com" , "linaro-mm-sig@lists.linaro.org" , "linux-mm@kvack.org" , "iommu@lists.linux-foundation.org" , "linux-tegra@vger.kernel.org" , "kyungmin.park@samsung.com" , "pullip.cho@samsung.com" , "linux-arm-kernel@lists.infradead.org" On 09/19/2012 07:44 PM, Krishna Reddy wrote: >> When a device driver would only use the IOMMU-API and needs small DMA- >> able areas it has to re-implement something like the DMA-API (basically an >> address allocator) for that. So I don't see a reason why both can't be used in a >> device driver. > > On Tegra, the following use cases need specific IOVA mapping. > 1. Few MMIO blocks need IOVA=PA mapping setup. In that case, why would we enable the IOMMU for that one device; IOMMU disabled means VA==PA, right? Perhaps isolation of the device so it can only access certain PA ranges for security? -- 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/ . Don't email: email@kvack.org