Em 28-02-2011 15:20, Mauro Carvalho Chehab escreveu:
> Em 28-02-2011 12:47, Jiri Slaby escreveu:
>> On 02/28/2011 03:53 PM, Konrad Rzeszutek Wilk wrote:
>>> On Mon, Feb 28, 2011 at 10:37:02AM +0100, 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
>>>
>>> Can you add a comment why you are fixing it? Is there a bug report for this?
>>> Under what conditions did you expose this fault?
>>
>> No, by a just peer review when I was looking for something completely
>> different.
>>
>>> You also might want to mention that "needn't be a physical address as
>>> a hardware IOMMU can (and most likely) will return a bus address where
>>> physical != bus address."
>>
>> Mauro, do you want me to resend this with such an udpate in the changelog?
>
> Having it properly documented is always a good idea, especially since a
> similar
> fix might be needed on other drivers that also need contiguous memory. While
> it
> currently is used only on devices embedded on hardware with no iommu, there
> are
> some x86 hardware that doesn't allow DMA scatter/gather.
>
> Btw, it may be worth to take a look at vb2 dma contig module, as it might have
> similar issues.
>
>>> Otherwise you can stick 'Reviewed-by: Konrad Rzeszutek Wilk
>>> <konrad.w...@oracle.com>'
>>> on it.
>
> Cheers,
> Mauro
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As I got no return, and the patch looked sane, I've reviewed the comment myself,
in order to make it more explicit, as suggested by Konrad, and added his
reviewed-by: tag:
Author: Jiri Slaby <jsl...@suse.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 <jsl...@suse.cz>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.w...@oracle.com>
Signed-off-by: Mauro Carvalho Chehab <mche...@redhat.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);
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