Re: [Xen-devel] [PATCH] usbfront: do not assume sequentially mapped pages

[Noboru Iwamatsu <n_iwamatsu@xxxxxxxxxxxxxx>]

Ian,

I tried out uvccapture-0.5, and I'm certain that we have the
same problem.

When uvccapture had started memcpy-ing from the v4l2_buffer, the 
v4l2_buffer was not filled yet.
(in line 294 of v4l2uvc.c, vd->buf.bytesused is less than HEADERFRAME1)

I'm uncertain whether this problem results from the isoc-transfer timing 
or v4l relating.
Regards,

Noboru

Ian Jackson wrote:
> Noboru Iwamatsu writes ("Re: [Xen-devel] [PATCH] usbfront: do not assume 
> sequentially mapped pages"):
> > Ian,
> >  > You might like to try a v4l uvc driver and see if it works for you.
> >
> > Sorry for the late reply.
> >
> > I've been trying USB2.0 UVC webcam too, but I have not succeeded yet.
> > I dumped urbs and saw no errors in isoc-urbs.
> I didn't see errors.  I ran uvccapture (as in Debian lenny), which
> seems to be the most simple test program available, and it segfaults
> while accessing what is supposed to be a buffer full of video data
> provided by mmapping the kernel's UVC driver.
>
> Ian.



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