From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-bw0-f46.google.com ([209.85.214.46]:60059 "EHLO mail-bw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755671Ab1CAIWb (ORCPT ); Tue, 1 Mar 2011 03:22:31 -0500 Message-ID: <4D6CACC2.7010307@gmail.com> Date: Tue, 01 Mar 2011 09:22:26 +0100 From: Jiri Slaby MIME-Version: 1.0 To: Jiri Slaby CC: mchehab@infradead.org, linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, Konrad Rzeszutek Wilk Subject: Re: [PATCH v2 1/1] V4L: videobuf, don't use dma addr as physical References: <1298967701-11889-1-git-send-email-jslaby@suse.cz> In-Reply-To: <1298967701-11889-1-git-send-email-jslaby@suse.cz> Content-Type: text/plain; charset=ISO-8859-2 Content-Transfer-Encoding: 7bit List-ID: Sender: On 03/01/2011 09:21 AM, Jiri Slaby wrote: > mem->dma_handle is a dma address obtained by dma_alloc_coherent which > needn't be a physical address as a hardware IOMMU can (and most > likely will) return a bus address where physical != bus address. 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. > > While at it, use PFN_DOWN instead of explicit shift to obtain a frame > number. > > This was discovered by a random review of the code when looking for > something completely different. I'm not aware of any bug reports for > this. > > However it is a bug because many v4l drivers use this layer and have > no idea whether IOMMU is in the system and running or not. > > Signed-off-by: Jiri Slaby > Cc: Mauro Carvalho Chehab > Cc: Konrad Rzeszutek Wilk Ah, this is rather: Acked-by: Konrad Rzeszutek Wilk > --- > > This is a version with updated changelog. > > 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); -- js