Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757411AbcCRPAd (ORCPT ); Fri, 18 Mar 2016 11:00:33 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:46097 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757066AbcCRPA3 (ORCPT ); Fri, 18 Mar 2016 11:00:29 -0400 Subject: Re: [PATCH 2/3] swiotlb: prefix dma_to_phys and phys_to_dma functions To: Robin Murphy , linux-arm-kernel@lists.infradead.org, timur@codeaurora.org, cov@codeaurora.org, nwatters@codeaurora.org References: <1458252137-24497-1-git-send-email-okaya@codeaurora.org> <1458252137-24497-2-git-send-email-okaya@codeaurora.org> <56EBF09A.1060503@arm.com> Cc: linux-mips@linux-mips.org, linux-ia64@vger.kernel.org, linux-xtensa@linux-xtensa.org, Catalin Marinas , Will Deacon , Max Filippov , Chris Metcalf , Paul Mackerras , "H. Peter Anvin" , Huacai Chen , Guan Xuetao , Marek Szyprowski , Jisheng Zhang , Florian Fainelli , Russell King , Aaro Koskinen , Michael Ellerman , x86@kernel.org, Ingo Molnar , Benjamin Herrenschmidt , Guenter Roeck , Fenghua Yu , Denys Vlasenko , Arnd Bergmann , Konrad Rzeszutek Wilk , Akinobu Mita , Bjorn Helgaas , Thomas Gleixner , Valentin Rothberg , Chris Zankel , Tony Luck , linux-pci@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, Dean Nelson , linux-kernel@vger.kernel.org, Ralf Baechle , "Suthikulpanit, Suravee" , Joe Perches , Andrew Morton From: Sinan Kaya Message-ID: <56EC1805.5060207@codeaurora.org> Date: Fri, 18 Mar 2016 11:00:21 -0400 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.7.0 MIME-Version: 1.0 In-Reply-To: <56EBF09A.1060503@arm.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2829 Lines: 69 On 3/18/2016 8:12 AM, Robin Murphy wrote: > Since we know for sure that swiotlb_to_phys is a no-op on arm64, it might be cleaner to simply not reference it at all. I suppose we could have some private local wrappers, e.g.: > > #define swiotlb_to_virt(addr) phys_to_virt((phys_addr_t)(addr)) > > to keep the intent of the code clear (and just in case anyone ever builds a system mad enough to warrant switching out that definition, but I'd hope that never happens). > > Otherwise, looks good - thanks for doing this! OK. I added this. Reviewed-by? I'm not happy to submit such a big patch for all different ARCHs. I couldn't find a cleaner solution. I'm willing to split this patch into multiple if there is a better way. diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c index ada00c3..8c0f66b 100644 --- a/arch/arm64/mm/dma-mapping.c +++ b/arch/arm64/mm/dma-mapping.c @@ -29,6 +29,14 @@ #include +/* + * If you are building a system without IOMMU, then you are using SWIOTLB + * library. The ARM64 adaptation of this library does not support address + * translation and it assumes that physical address = dma address for such + * a use case. Please don't build a platform that violates this. + */ +#define swiotlb_to_virt(addr) phys_to_virt((phys_addr_t)(addr)) + static pgprot_t __get_dma_pgprot(struct dma_attrs *attrs, pgprot_t prot, bool coherent) { @@ -188,7 +196,7 @@ static void __dma_free(struct device *dev, size_t size, void *vaddr, dma_addr_t dma_handle, struct dma_attrs *attrs) { - void *swiotlb_addr = phys_to_virt(swiotlb_dma_to_phys(dev, dma_handle)); + void *swiotlb_addr = swiotlb_to_virt(dma_handle); size = PAGE_ALIGN(size); @@ -209,8 +217,7 @@ static dma_addr_t __swiotlb_map_page(struct device *dev, struct page *page, dev_addr = swiotlb_map_page(dev, page, offset, size, dir, attrs); if (!is_device_dma_coherent(dev)) - __dma_map_area(phys_to_virt(swiotlb_dma_to_phys(dev, dev_addr)), - size, dir); + __dma_map_area(swiotlb_to_virt(dev_addr), size, dir); return dev_addr; } @@ -283,8 +290,7 @@ static void __swiotlb_sync_single_for_device(struct device *dev, { swiotlb_sync_single_for_device(dev, dev_addr, size, dir); if (!is_device_dma_coherent(dev)) - __dma_map_area(phys_to_virt(swiotlb_dma_to_phys(dev, dev_addr)), - size, dir); + __dma_map_area(swiotlb_to_virt(dev_addr), size, dir); } -- Sinan Kaya Qualcomm Technologies, Inc. on behalf of Qualcomm Innovation Center, Inc. Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project