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=-3.5 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 DAFF7C433DF for ; Wed, 10 Jun 2020 07:24:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AAB8E2064C for ; Wed, 10 Jun 2020 07:24:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="YFULLve1" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726285AbgFJHY5 (ORCPT ); Wed, 10 Jun 2020 03:24:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54190 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726081AbgFJHY5 (ORCPT ); Wed, 10 Jun 2020 03:24:57 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F0D5BC03E96B; Wed, 10 Jun 2020 00:24:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=6c/vE/ozxTPwS24BUkYxi15LaZy1is3YVzeL7qEF/KU=; b=YFULLve167EFJAUFIFsBXuS464 4Jdpz0CHZIZV99sZXhwNfjkc0tbGoC8x5EHEe5oCi0RMjn8Yn48HVzwOTatYxuWFlGVAicqgPCoIr FbDj4HlG7sW61Wcc9mGwBHLqWWsp/DjpHH0mgdWLLZKv0PH1SRnL/gvL7ygJx9RnPNXzFHq0fmm85 fGVfLeXUUKn+UU/6hx4L7zrN/HbBNo8I/Y6edXdqCqGJLSyhd7nUyL14kxthvpTgBQ6zSv16a261R QbmU2cU6oUks3aM4x49C3FsnOGUa26mxaTTQuZs5vpOen8MhMhVqVdo6+1LPv/EPMa6la3219xAEy jxC9aLlw==; Received: from hch by bombadil.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1jiv6K-0001gz-CH; Wed, 10 Jun 2020 07:24:44 +0000 Date: Wed, 10 Jun 2020 00:24:44 -0700 From: Christoph Hellwig To: Vladimir Murzin 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 Subject: Re: [PATCH 2/2] arm-nommu: Add use_reserved_mem() to check if device support reserved memory Message-ID: <20200610072444.GA6293@infradead.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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <90df5646-e0c4-fcac-d934-4cc922230dd2@arm.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org 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..) 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 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) {