From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0589FC282D8 for ; Fri, 1 Feb 2019 14:22:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CE70F218AC for ; Fri, 1 Feb 2019 14:22:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730199AbfBAOWv (ORCPT ); Fri, 1 Feb 2019 09:22:51 -0500 Received: from foss.arm.com ([217.140.101.70]:60670 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726915AbfBAOWu (ORCPT ); Fri, 1 Feb 2019 09:22:50 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id B4D3780D; Fri, 1 Feb 2019 06:22:49 -0800 (PST) Received: from [10.1.196.75] (e110467-lin.cambridge.arm.com [10.1.196.75]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 5BE763F59C; Fri, 1 Feb 2019 06:22:48 -0800 (PST) Subject: Re: [PATCH 01/19] dma-mapping: add a Kconfig symbol to indicated arch_dma_prep_coherent presence To: Christoph Hellwig Cc: Joerg Roedel , Catalin Marinas , Will Deacon , Tom Lendacky , iommu@lists.linux-foundation.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <20190114094159.27326-1-hch@lst.de> <20190114094159.27326-2-hch@lst.de> From: Robin Murphy Message-ID: Date: Fri, 1 Feb 2019 14:22:46 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <20190114094159.27326-2-hch@lst.de> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 14/01/2019 09:41, Christoph Hellwig wrote: > Add a Kconfig symbol that indicates an architecture provides a > arch_dma_prep_coherent implementation, and provide a stub otherwise. > > This will allow the generic dma-iommu code to it while still allowing > to be built for cache coherent architectures. I've been pondering this for a while now, and I still can't really come up with a case where arch_dma_prep_coherent() would need to behave differently from arch_sync_dma_for_device(..., DMA_BIDIRECTIONAL). I wonder if we could just save ourselves this little bit of complexity by using that instead... Robin. > Signed-off-by: Christoph Hellwig > --- > arch/arm64/Kconfig | 1 + > arch/csky/Kconfig | 1 + > include/linux/dma-noncoherent.h | 6 ++++++ > kernel/dma/Kconfig | 3 +++ > 4 files changed, 11 insertions(+) > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index a4168d366127..ae3f581a9bcc 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -13,6 +13,7 @@ config ARM64 > select ARCH_HAS_DEVMEM_IS_ALLOWED > select ARCH_HAS_DMA_COHERENT_TO_PFN > select ARCH_HAS_DMA_MMAP_PGPROT > + select ARCH_HAS_DMA_PREP_COHERENT > select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI > select ARCH_HAS_ELF_RANDOMIZE > select ARCH_HAS_FAST_MULTIPLIER > diff --git a/arch/csky/Kconfig b/arch/csky/Kconfig > index 398113c845f5..8b84d4362ff6 100644 > --- a/arch/csky/Kconfig > +++ b/arch/csky/Kconfig > @@ -1,5 +1,6 @@ > config CSKY > def_bool y > + select ARCH_HAS_DMA_PREP_COHERENT > select ARCH_HAS_SYNC_DMA_FOR_CPU > select ARCH_HAS_SYNC_DMA_FOR_DEVICE > select ARCH_USE_BUILTIN_BSWAP > diff --git a/include/linux/dma-noncoherent.h b/include/linux/dma-noncoherent.h > index 69b36ed31a99..9741767e400f 100644 > --- a/include/linux/dma-noncoherent.h > +++ b/include/linux/dma-noncoherent.h > @@ -72,6 +72,12 @@ static inline void arch_sync_dma_for_cpu_all(struct device *dev) > } > #endif /* CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU_ALL */ > > +#ifdef CONFIG_ARCH_HAS_DMA_PREP_COHERENT > void arch_dma_prep_coherent(struct page *page, size_t size); > +#else > +static inline void arch_dma_prep_coherent(struct page *page, size_t size) > +{ > +} > +#endif /* CONFIG_ARCH_HAS_DMA_PREP_COHERENT */ > > #endif /* _LINUX_DMA_NONCOHERENT_H */ > diff --git a/kernel/dma/Kconfig b/kernel/dma/Kconfig > index ca88b867e7fe..541128a32c5d 100644 > --- a/kernel/dma/Kconfig > +++ b/kernel/dma/Kconfig > @@ -29,6 +29,9 @@ config ARCH_HAS_SYNC_DMA_FOR_CPU > config ARCH_HAS_SYNC_DMA_FOR_CPU_ALL > bool > > +config ARCH_HAS_DMA_PREP_COHERENT > + bool > + > config ARCH_HAS_DMA_COHERENT_TO_PFN > bool > >