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.wilk@xxxxxxxxxx>' >>> on it. > > Cheers, > Mauro > -- > To unsubscribe from this list: send the line "unsubscribe linux-media" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html 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 <jslaby@xxxxxxx> 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@xxxxxxx> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx> 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); -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
