Hi Bhupesh,
On Thursday 28 March 2013 18:39:54 Bhupesh SHARMA wrote:
> > On Thursday 28 March 2013 15:11:52 Bhupesh Sharma wrote:
> > > This patch reworks the videobuffer management logic present in the UVC
> > > webcam gadget and ports it to use the "more apt" videobuf2 framework
> > > for video buffer management.
> > >
> > > To support routing video data captured from a real V4L2 video capture
> > > device with a "zero copy" operation on videobuffers (as they pass from
> > > the V4L2 domain to UVC domain via a user-space application), we need
> > > to support USER_PTR IO method at the UVC gadget side.
> > >
> > > So the V4L2 capture device driver can still continue to use MMAP IO
> > > method and now the user-space application can just pass a pointer to
> > > the video buffers being dequeued from the V4L2 device side while
> > > queueing them at the UVC gadget end. This ensures that we have a "zero-
> > > copy" design as the videobuffers pass from the V4L2 capture device to
> > > the UVC gadget.
> > >
> > > Note that there will still be a need to apply UVC specific payload
> > > headers on top of each UVC payload data, which will still require a
> > > copy operation to be performed in the 'encode' routines of the UVC
> > > gadget.
> > >
> > > This patch also addresses one issue found out while porting the UVC
> > >
> > > gadget to videobuf2 framework:
> > > - In case the usb requests queued by the gadget get completed
> > >
> > > with a status of -ESHUTDOWN (disconnected from host),
> > > the queue of videobuf2 should be cancelled to ensure that the
> > > application space daemon is not left in a state waiting for
> > > a vb2 to be successfully absorbed at the USB side.
> > >
> > > Signed-off-by: Bhupesh Sharma <bhupesh.sha...@st.com>
> >
> > Finally,
> >
> > Acked-by: Laurent Pinchart <laurent.pinch...@ideasonboard.com>
> >
> > :-)
>
> Thanks for your time in reviewing this and previous patchsets :).
You're welcome.
> If you can apply these 2 patches to your git tree
> (git://linuxtv.org/pinchartl/uvcvideo.git),
Done. They're in the uvc-gadget branch, based on Felipe's master branch.
> I want to prepare and send out two more UVC patches:
> - One that supports UVC Bulk endpoint implementation.
> - Second that supports MEMCPY less implementation for adding UVC header to
> the UVC payload for UDC controllers which support SG implementation.
>
> In the meantime, probably we can request Felipe to pull UVC gadget related
> patches from your git repo.
Felipe, can you pull from
git://linuxtv.org/pinchartl/uvcvideo.git uvc-gadget branch
or do you want a proper pull request ?
--
Regards,
Laurent Pinchart
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