Messages in this thread Patch in this message | | | From | Laurent Pinchart <> | 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 |
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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 <jslaby@suse.cz> > Cc: Mauro Carvalho Chehab <mchehab@infradead.org> > Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> > --- > 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
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