From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: [PATCH v2 14/31] arm64: DMA mapping API Date: Wed, 15 Aug 2012 16:16:00 +0000 Message-ID: <201208151616.01114.arnd@arndb.de> References: <1344966752-16102-1-git-send-email-catalin.marinas@arm.com> <1344966752-16102-15-git-send-email-catalin.marinas@arm.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Return-path: Received: from moutng.kundenserver.de ([212.227.126.187]:49957 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751921Ab2HOQQG (ORCPT ); Wed, 15 Aug 2012 12:16:06 -0400 In-Reply-To: <1344966752-16102-15-git-send-email-catalin.marinas@arm.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Catalin Marinas Cc: linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org On Tuesday 14 August 2012, Catalin Marinas wrote: > +static struct dma_map_ops arm64_swiotlb_dma_ops = { > + .alloc = arm64_swiotlb_alloc_coherent, > + .free = arm64_swiotlb_free_coherent, > + .map_page = arm64_swiotlb_map_page, > + .unmap_page = arm64_swiotlb_unmap_page, > + .map_sg = arm64_swiotlb_map_sg_attrs, > + .unmap_sg = arm64_swiotlb_unmap_sg_attrs, > + .sync_single_for_cpu = arm64_swiotlb_sync_single_for_cpu, > + .sync_single_for_device = arm64_swiotlb_sync_single_for_device, > + .sync_sg_for_cpu = arm64_swiotlb_sync_sg_for_cpu, > + .sync_sg_for_device = arm64_swiotlb_sync_sg_for_device, > + .dma_supported = swiotlb_dma_supported, > + .mapping_error = swiotlb_dma_mapping_error, > +}; > + > +void __init swiotlb_init_with_default_size(size_t default_size, int verbose); > + > +void __init arm64_swiotlb_init(size_t max_size) > +{ > + dma_ops = &arm64_swiotlb_dma_ops; > + swiotlb_init_with_default_size(min((size_t)SZ_64M, max_size), 1); > +} Why is swiotlb the default? I would expect that most devices can in fact use the entire 64 bit address space, so you can use a simple linear implementation for those. Arnd From mboxrd@z Thu Jan 1 00:00:00 1970 From: arnd@arndb.de (Arnd Bergmann) Date: Wed, 15 Aug 2012 16:16:00 +0000 Subject: [PATCH v2 14/31] arm64: DMA mapping API In-Reply-To: <1344966752-16102-15-git-send-email-catalin.marinas@arm.com> References: <1344966752-16102-1-git-send-email-catalin.marinas@arm.com> <1344966752-16102-15-git-send-email-catalin.marinas@arm.com> Message-ID: <201208151616.01114.arnd@arndb.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tuesday 14 August 2012, Catalin Marinas wrote: > +static struct dma_map_ops arm64_swiotlb_dma_ops = { > + .alloc = arm64_swiotlb_alloc_coherent, > + .free = arm64_swiotlb_free_coherent, > + .map_page = arm64_swiotlb_map_page, > + .unmap_page = arm64_swiotlb_unmap_page, > + .map_sg = arm64_swiotlb_map_sg_attrs, > + .unmap_sg = arm64_swiotlb_unmap_sg_attrs, > + .sync_single_for_cpu = arm64_swiotlb_sync_single_for_cpu, > + .sync_single_for_device = arm64_swiotlb_sync_single_for_device, > + .sync_sg_for_cpu = arm64_swiotlb_sync_sg_for_cpu, > + .sync_sg_for_device = arm64_swiotlb_sync_sg_for_device, > + .dma_supported = swiotlb_dma_supported, > + .mapping_error = swiotlb_dma_mapping_error, > +}; > + > +void __init swiotlb_init_with_default_size(size_t default_size, int verbose); > + > +void __init arm64_swiotlb_init(size_t max_size) > +{ > + dma_ops = &arm64_swiotlb_dma_ops; > + swiotlb_init_with_default_size(min((size_t)SZ_64M, max_size), 1); > +} Why is swiotlb the default? I would expect that most devices can in fact use the entire 64 bit address space, so you can use a simple linear implementation for those. Arnd