Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754098AbcLIPgi (ORCPT ); Fri, 9 Dec 2016 10:36:38 -0500 Received: from foss.arm.com ([217.140.101.70]:59426 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752511AbcLIPgh (ORCPT ); Fri, 9 Dec 2016 10:36:37 -0500 Subject: Re: [PATCH] nommu: allow mmap when !CONFIG_MMU To: Benjamin Gaignard , linux@armlinux.org.uk, linux-arm-kernel@lists.infradead.org, Linux Kernel Mailing List , Robin.Murphy@arm.com References: <1480600080-30196-1-git-send-email-benjamin.gaignard@linaro.org> Cc: Catalin Marinas , Arnd Bergmann From: Vladimir Murzin Message-ID: <584ACF82.5090609@arm.com> Date: Fri, 9 Dec 2016 15:36:34 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1451 Lines: 43 On 09/12/16 15:27, Benjamin Gaignard wrote: > + Vladimir I'm not in DMA, but I can see that with your patch it deviates from dma_common_mmap(), can you give more context, please? Cheers Vladimir > > 2016-12-01 14:48 GMT+01:00 Benjamin Gaignard : >> commit ab6494f0c96f ("nommu: Add noMMU support to the DMA API") have >> add CONFIG_MMU compilation flag but that prohibit to use dma_mmap_wc() >> when the platform doesn't have MMU. >> >> This patch call vm_iomap_memory() in noMMU case to test if addresses >> are correct and set wma->vm_flags rather than all return an error. >> >> Signed-off-by: Benjamin Gaignard >> Cc: Catalin Marinas >> Cc: arnd@arndb.de >> --- >> arch/arm/mm/dma-mapping.c | 3 +++ >> 1 file changed, 3 insertions(+) >> >> diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c >> index ab4f745..230875e 100644 >> --- a/arch/arm/mm/dma-mapping.c >> +++ b/arch/arm/mm/dma-mapping.c >> @@ -868,6 +868,9 @@ static int __arm_dma_mmap(struct device *dev, struct vm_area_struct *vma, >> vma->vm_end - vma->vm_start, >> vma->vm_page_prot); >> } >> +#else >> + ret = vm_iomap_memory(vma, vma->vm_start, >> + (vma->vm_end - vma->vm_start)); >> #endif /* CONFIG_MMU */ >> >> return ret; >> -- >> 1.9.1 >> >