Hi Arnout, Just a very minor style comment. > -----Original Message----- > From: linux-media-owner@xxxxxxxxxxxxxxx [mailto:linux-media- > owner@xxxxxxxxxxxxxxx] On Behalf Of Arnout Vandecappelle > Sent: Wednesday, March 17, 2010 5:53 PM > To: linux-media@xxxxxxxxxxxxxxx; mchehab@xxxxxxxxxxxxx; arnout@xxxxxxx > Subject: [PATCH 2/2] V4L/DVB: buf-dma-sg.c: support non-pageable user- > allocated memory > > videobuf_dma_init_user_locked() uses get_user_pages() to get the > virtual-to-physical address mapping for user-allocated memory. > However, the user-allocated memory may be non-pageable because it > is an I/O range or similar. get_user_pages() fails with -EFAULT > in that case. > > If the user-allocated memory is physically contiguous, the approach > of V4L2_MEMORY_OVERLAY can be used. If it is not, -EFAULT is still > returned. > --- > drivers/media/video/videobuf-dma-sg.c | 18 ++++++++++++++++++ > 1 files changed, 18 insertions(+), 0 deletions(-) > > diff --git a/drivers/media/video/videobuf-dma-sg.c > b/drivers/media/video/videobuf-dma-sg.c > index 18aaf54..bd2d95d 100644 > --- a/drivers/media/video/videobuf-dma-sg.c > +++ b/drivers/media/video/videobuf-dma-sg.c > @@ -136,6 +136,7 @@ static int videobuf_dma_init_user_locked(struct > videobuf_dmabuf *dma, > { > unsigned long first,last; > int err, rw = 0; > + struct vm_area_struct *vma; > > dma->direction = direction; > switch (dma->direction) { > @@ -153,6 +154,23 @@ static int videobuf_dma_init_user_locked(struct > videobuf_dmabuf *dma, > last = ((data+size-1) & PAGE_MASK) >> PAGE_SHIFT; > dma->offset = data & ~PAGE_MASK; > dma->nr_pages = last-first+1; > + > + /* In case the buffer is user-allocated and is actually an IO buffer > for > + some other hardware, we cannot map pages for it. It in fact > behaves > + the same as an overlay. */ > + vma = find_vma (current->mm, data); Remove space before parenthesis above, so it becomes: vma = find_vma(current->mm, data); Regards, Sergio > + if (vma && (vma->vm_flags & VM_IO)) { > + /* Only a single contiguous buffer is supported. */ > + if (vma->vm_end < data + size) { > + dprintk(1, "init user: non-contiguous IO buffer.\n"); > + return -EFAULT; /* same error that get_user_pages() > would give */ > + } > + dma->bus_addr = (vma->vm_pgoff << PAGE_SHIFT) + (data - vma- > >vm_start); > + dprintk(1,"init user IO [0x%lx+0x%lx => %d pages at 0x%x]\n", > + data, size, dma->nr_pages, dma->bus_addr); > + return 0; > + } > + > dma->pages = kmalloc(dma->nr_pages * sizeof(struct page*), > GFP_KERNEL); > if (NULL == dma->pages) > -- > 1.6.3.3 > > -- > 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 -- 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
