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    SubjectRe: [PATCH] Video/UVC: Port mainlined uvc video driver to NOMMU
    Date
    Hi Bryan, Michael,

    On Thursday 06 November 2008, Bryan Wu wrote:
    > From: Michael Hennerich <michael.hennerich@analog.com>
    >
    > Add NOMMU mmap support.
    >
    > Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
    > Signed-off-by: Bryan Wu <cooloney@kernel.org>
    > ---
    > drivers/media/video/uvc/uvc_v4l2.c | 14 ++++++++++++++
    > 1 files changed, 14 insertions(+), 0 deletions(-)
    >
    > diff --git a/drivers/media/video/uvc/uvc_v4l2.c
    > b/drivers/media/video/uvc/uvc_v4l2.c index 758dfef..2237f5e 100644
    > --- a/drivers/media/video/uvc/uvc_v4l2.c
    > +++ b/drivers/media/video/uvc/uvc_v4l2.c
    > @@ -1050,6 +1050,7 @@ static int uvc_v4l2_mmap(struct file *file, struct
    > vm_area_struct *vma) break;
    > }
    >
    > +#ifdef CONFIG_MMU
    > if (i == video->queue.count || size != video->queue.buf_size) {
    > ret = -EINVAL;
    > goto done;
    > @@ -1071,7 +1072,20 @@ static int uvc_v4l2_mmap(struct file *file, struct
    > vm_area_struct *vma) addr += PAGE_SIZE;
    > size -= PAGE_SIZE;
    > }
    > +#else
    > + if (i == video->queue.count ||
    > + PAGE_ALIGN(size) != video->queue.buf_size) {

    Just out of curiosity, why do you need to PAGE_ALIGN size for non-MMU
    platforms ?

    > + ret = -EINVAL;
    > + goto done;
    > + }
    > +
    > + vma->vm_flags |= VM_IO | VM_MAYSHARE; /* documentation/nommu-mmap.txt */

    VM_MAYSHARE is not documented anywhere in Documentation/ in Linux 2.6.28-rc3.
    Why is it needed for non-MMU architectures only ?

    > +
    > + addr = (unsigned long)video->queue.mem + buffer->buf.m.offset;
    >
    > + vma->vm_start = addr;
    > + vma->vm_end = addr + video->queue.buf_size;
    > +#endif
    > vma->vm_ops = &uvc_vm_ops;
    > vma->vm_private_data = buffer;
    > uvc_vm_open(vma);

    Best regards,

    Laurent Pinchart


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