From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753549Ab1B1KxW (ORCPT ); Mon, 28 Feb 2011 05:53:22 -0500 Received: from perceval.ideasonboard.com ([95.142.166.194]:52679 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753449Ab1B1KxV (ORCPT ); Mon, 28 Feb 2011 05:53:21 -0500 From: Laurent Pinchart To: Jiri Slaby Subject: Re: [PATCH v2 -resend#1 1/1] V4L: videobuf, don't use dma addr as physical Date: Mon, 28 Feb 2011 11:53:30 +0100 User-Agent: KMail/1.13.6 (Linux/2.6.37-gentoo; KDE/4.6.0; x86_64; ; ) Cc: mchehab@infradead.org, linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, jirislaby@gmail.com, Konrad Rzeszutek Wilk References: <1298885822-10083-1-git-send-email-jslaby@suse.cz> In-Reply-To: <1298885822-10083-1-git-send-email-jslaby@suse.cz> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-15" Content-Transfer-Encoding: 7bit Message-Id: <201102281153.30585.laurent.pinchart@ideasonboard.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Jiri, On Monday 28 February 2011 10:37:02 Jiri Slaby wrote: > mem->dma_handle is a dma address obtained by dma_alloc_coherent which > needn't be a physical address in presence of IOMMU. So ensure we are > remapping (remap_pfn_range) the right page in __videobuf_mmap_mapper > by using virt_to_phys(mem->vaddr) and not mem->dma_handle. Quoting arch/arm/include/asm/memory.h, /* * These are *only* valid on the kernel direct mapped RAM memory. * Note: Drivers should NOT use these. They are the wrong * translation for translating DMA addresses. Use the driver * DMA support - see dma-mapping.h. */ static inline unsigned long virt_to_phys(const volatile void *x) { return __virt_to_phys((unsigned long)(x)); } Why would you use physically contiguous memory if you have an IOMMU anyway ? > While at it, use PFN_DOWN instead of explicit shift. > > Signed-off-by: Jiri Slaby > Cc: Mauro Carvalho Chehab > Cc: Konrad Rzeszutek Wilk > --- > drivers/media/video/videobuf-dma-contig.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/drivers/media/video/videobuf-dma-contig.c > b/drivers/media/video/videobuf-dma-contig.c index c969111..19d3e4a 100644 > --- a/drivers/media/video/videobuf-dma-contig.c > +++ b/drivers/media/video/videobuf-dma-contig.c > @@ -300,7 +300,7 @@ static int __videobuf_mmap_mapper(struct videobuf_queue > *q, > > vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); > retval = remap_pfn_range(vma, vma->vm_start, > - mem->dma_handle >> PAGE_SHIFT, > + PFN_DOWN(virt_to_phys(mem->vaddr)) > size, vma->vm_page_prot); > if (retval) { > dev_err(q->dev, "mmap: remap failed with error %d. ", retval); -- Regards, Laurent Pinchart