Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754804AbcC1S3g (ORCPT ); Mon, 28 Mar 2016 14:29:36 -0400 Received: from mail-ig0-f193.google.com ([209.85.213.193]:34785 "EHLO mail-ig0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750850AbcC1S3a (ORCPT ); Mon, 28 Mar 2016 14:29:30 -0400 MIME-Version: 1.0 In-Reply-To: <56EC1805.5060207@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> <56EC1805.5060207@codeaurora.org> Date: Mon, 28 Mar 2016 14:29:29 -0400 X-Google-Sender-Auth: PSJjowJ684DP3gHFgpI9R9xUe_g Message-ID: Subject: Re: [PATCH 2/3] swiotlb: prefix dma_to_phys and phys_to_dma functions From: Konrad Rzeszutek Wilk To: Sinan Kaya Cc: Robin Murphy , linux-arm-kernel@lists.infradead.org, timur@codeaurora.org, cov@codeaurora.org, nwatters@codeaurora.org, 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 , 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 , LKML , Ralf Baechle , "Suthikulpanit, Suravee" , Joe Perches , Andrew Morton , Stefano Stabellini Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3110 Lines: 76 On Fri, Mar 18, 2016 at 11:00 AM, Sinan Kaya wrote: > 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. > + */ Why not just expand the ARM64 part to support address translation? > +#define swiotlb_to_virt(addr) phys_to_virt((phys_addr_t)(addr)) > + Adding Stefano here. > 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