From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx175.postini.com [74.125.245.175]) by kanga.kvack.org (Postfix) with SMTP id D11A86B002B for ; Mon, 15 Oct 2012 20:50:17 -0400 (EDT) Received: by mail-vb0-f41.google.com with SMTP id v13so7029949vbk.14 for ; Mon, 15 Oct 2012 17:50:16 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <1350309832-18461-1-git-send-email-m.szyprowski@samsung.com> References: <1350309832-18461-1-git-send-email-m.szyprowski@samsung.com> Date: Tue, 16 Oct 2012 09:50:16 +0900 Message-ID: Subject: Re: [RFC 0/2] DMA-mapping & IOMMU - physically contiguous allocations From: Inki Dae Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: Marek Szyprowski Cc: linux-arm-kernel@lists.infradead.org, linaro-mm-sig@lists.linaro.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Kyungmin Park , Arnd Bergmann , Russell King - ARM Linux , Rob Clark 2012/10/15 Marek Szyprowski : > Hello, > > Some devices, which have IOMMU, for some use cases might require to > allocate a buffers for DMA which is contiguous in physical memory. Such > use cases appears for example in DRM subsystem when one wants to improve > performance or use secure buffer protection. > > I would like to ask if adding a new attribute, as proposed in this RFC > is a good idea? I feel that it might be an attribute just for a single > driver, but I would like to know your opinion. Should we look for other > solution? > In addition, currently we have worked dma-mapping-based iommu support for exynos drm driver with this patch set so this patch set has been tested with iommu enabled exynos drm driver and worked fine. actually, this feature is needed for secure mode such as TrustZone. in case of Exynos SoC, memory region for secure mode should be physically contiguous and also maybe OMAP but now dma-mapping framework doesn't guarantee physically continuous memory allocation so this patch set would make it possible. Tested-by: Inki Dae Reviewed-by: Inki Dae Thanks, Inki Dae > Best regards > -- > Marek Szyprowski > Samsung Poland R&D Center > > > Marek Szyprowski (2): > common: DMA-mapping: add DMA_ATTR_FORCE_CONTIGUOUS attribute > ARM: dma-mapping: add support for DMA_ATTR_FORCE_CONTIGUOUS attribute > > Documentation/DMA-attributes.txt | 9 +++++++++ > arch/arm/mm/dma-mapping.c | 41 ++++++++++++++++++++++++++++++-------- > include/linux/dma-attrs.h | 1 + > 3 files changed, 43 insertions(+), 8 deletions(-) > > -- > 1.7.9.5 > > -- > 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 -- 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