linux-kernel - Re: [PATCH v2 -resend#1 1/1] V4L: videobuf, don't use dma addr as physical

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Date:	Mon, 21 Mar 2011 23:55:24 +0100
From:	Jiri Slaby <jslaby@...e.cz>
To:	Mauro Carvalho Chehab <maurochehab@...il.com>
CC:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
	jirislaby@...il.com
Subject: Re: [PATCH v2 -resend#1 1/1] V4L: videobuf, don't use dma addr as
 physical

On 03/21/2011 11:43 PM, Mauro Carvalho Chehab wrote:
> As I got no return, and the patch looked sane, I've reviewed the comment myself,

Aha, I forgot to send it. Sorry.

It looks OK.

> Author: Jiri Slaby <jslaby@...e.cz>
> Date:   Mon Feb 28 06:37:02 2011 -0300
> 
>     [media] V4L: videobuf, don't use dma addr as physical
>     
>     mem->dma_handle is a dma address obtained by dma_alloc_coherent which
>     needn't be a physical address in presence of IOMMU, 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.
>     
>     Signed-off-by: Jiri Slaby <jslaby@...e.cz>
>     Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
>     Signed-off-by: Mauro Carvalho Chehab <mchehab@...hat.com>
> 
> 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);

thanks,
-- 
js
suse labs
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