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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 54BFFC433E1 for ; Wed, 10 Jun 2020 08:19:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 39B0B2085B for ; Wed, 10 Jun 2020 08:19:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726670AbgFJITu (ORCPT ); Wed, 10 Jun 2020 04:19:50 -0400 Received: from foss.arm.com ([217.140.110.172]:54646 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726278AbgFJITu (ORCPT ); Wed, 10 Jun 2020 04:19:50 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 9A88C1F1; Wed, 10 Jun 2020 01:19:49 -0700 (PDT) Received: from [10.57.43.21] (unknown [10.57.43.21]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id E74FE3F6CF; Wed, 10 Jun 2020 01:19:46 -0700 (PDT) Subject: Re: [PATCH 2/2] arm-nommu: Add use_reserved_mem() to check if device support reserved memory To: Christoph Hellwig Cc: dillon.minfei@gmail.com, robh+dt@kernel.org, mcoquelin.stm32@gmail.com, alexandre.torgue@st.com, linux@armlinux.org.uk, kstewart@linuxfoundation.org, allison@lohutok.net, info@metux.net, tglx@linutronix.de, devicetree@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <1591605038-8682-1-git-send-email-dillon.minfei@gmail.com> <1591605038-8682-3-git-send-email-dillon.minfei@gmail.com> <90df5646-e0c4-fcac-d934-4cc922230dd2@arm.com> <20200610072444.GA6293@infradead.org> From: Vladimir Murzin Message-ID: <9c3a7b4e-0190-e9bb-91fe-6d5692559888@arm.com> Date: Wed, 10 Jun 2020 09:19:45 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20200610072444.GA6293@infradead.org> Content-Type: text/plain; charset=utf-8 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 6/10/20 8:24 AM, Christoph Hellwig wrote: > Ok, I finally found the original patch from Vladimir. Comments below: > >> +++ b/kernel/dma/direct.c >> @@ -456,14 +456,14 @@ int dma_direct_mmap(struct device *dev, struct vm_area_struct *vma, >> #else /* CONFIG_MMU */ >> bool dma_direct_can_mmap(struct device *dev) >> { >> - return false; >> + return true; >> } >> >> int dma_direct_mmap(struct device *dev, struct vm_area_struct *vma, >> void *cpu_addr, dma_addr_t dma_addr, size_t size, >> unsigned long attrs) >> { >> - return -ENXIO; >> + return vm_iomap_memory(vma, vma->vm_start, (vma->vm_end - vma->vm_start));; > > I think we should try to reuse the mmu dma_direct_mmap implementation, > which does about the same. This version has been compile tested on > arm-nommu only, let me know what you think: (btw, a nommu_defconfig of > some kind for arm would be nice..) Catch-all nommu_defconfig is not easy for ARM, AFAIK folk carry few hacks for randconfig... Meanwhile, known working NOMMU configs $ git grep "# CONFIG_MMU is not set" arch/arm/configs/ arch/arm/configs/efm32_defconfig:# CONFIG_MMU is not set arch/arm/configs/lpc18xx_defconfig:# CONFIG_MMU is not set arch/arm/configs/mps2_defconfig:# CONFIG_MMU is not set arch/arm/configs/stm32_defconfig:# CONFIG_MMU is not set arch/arm/configs/vf610m4_defconfig:# CONFIG_MMU is not set > > diff --git a/kernel/dma/Kconfig b/kernel/dma/Kconfig > index d006668c0027d2..e0dae570a51530 100644 > --- a/kernel/dma/Kconfig > +++ b/kernel/dma/Kconfig > @@ -71,6 +71,7 @@ config SWIOTLB > # in the pagetables > # > config DMA_NONCOHERENT_MMAP > + default y if !MMU > bool Nit: def_bool !MMU > > config DMA_REMAP > diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c > index 0a4881e59aa7d6..9ec6a5c3fc578c 100644 > --- a/kernel/dma/direct.c > +++ b/kernel/dma/direct.c > @@ -459,7 +459,6 @@ int dma_direct_get_sgtable(struct device *dev, struct sg_table *sgt, > return ret; > } > > -#ifdef CONFIG_MMU > bool dma_direct_can_mmap(struct device *dev) > { > return dev_is_dma_coherent(dev) || > @@ -485,19 +484,6 @@ int dma_direct_mmap(struct device *dev, struct vm_area_struct *vma, > return remap_pfn_range(vma, vma->vm_start, pfn + vma->vm_pgoff, > user_count << PAGE_SHIFT, vma->vm_page_prot); > } > -#else /* CONFIG_MMU */ > -bool dma_direct_can_mmap(struct device *dev) > -{ > - return false; > -} > - > -int dma_direct_mmap(struct device *dev, struct vm_area_struct *vma, > - void *cpu_addr, dma_addr_t dma_addr, size_t size, > - unsigned long attrs) > -{ > - return -ENXIO; > -} > -#endif /* CONFIG_MMU */ > > int dma_direct_supported(struct device *dev, u64 mask) > { > LGTM. FWIW: Reviewed-by: Vladimir Murzin