Re: [PATCH 1/2] v4l: added V4L2_BUF_FLAG_EOS flag indicating the last frame in the stream

[Andrzej Hajda <a.hajda@samsung.com>]

On Mon, 2012-06-18 at 08:24 -0300, Mauro Carvalho Chehab wrote:
> Em 22-05-2012 12:33, Andrzej Hajda escreveu:
> > Some devices requires indicator if the buffer is the last one in the stream.
> > Applications and drivers can use this flag in such case.
> > 
> > Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
> > Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
> > ---
> >   Documentation/DocBook/media/v4l/io.xml          |    7 +++++++
> >   Documentation/DocBook/media/v4l/vidioc-qbuf.xml |    2 ++
> >   include/linux/videodev2.h                       |    1 +
> >   3 files changed, 10 insertions(+), 0 deletions(-)
> > 
> > diff --git a/Documentation/DocBook/media/v4l/io.xml b/Documentation/DocBook/media/v4l/io.xml
> > index fd6aca2..dcbf1e0 100644
> > --- a/Documentation/DocBook/media/v4l/io.xml
> > +++ b/Documentation/DocBook/media/v4l/io.xml
> > @@ -956,6 +956,13 @@ Typically applications shall use this flag for output buffers if the data
> >   in this buffer has not been created by the CPU but by some DMA-capable unit,
> >   in which case caches have not been used.</entry>
> >   	  </row>
> > +	  <row>
> > +	    <entry><constant>V4L2_BUF_FLAG_EOS</constant></entry>
> > +	    <entry>0x2000</entry>
> > +	    <entry>Application should set this flag in the output buffer
> > +in order to inform the driver about the last frame of the stream. Some
> > +drivers may require it to properly finish processing the stream.</entry>
> 
> This breaks backward compatibility, as applications written before this change
> won't set this flag.

I am preparing a new patch which will use VIDIOC_ENCODER_CMD with
command V4L2_ENC_CMD_STOP and a new flag
V4L2_ENC_CMD_STOP_AFTER_NEXT_FRAME, according to suggestions by Hans
Verkuil. Discussion is at thread started from the parent email (subject
"[PATCH 0/2] s5p-mfc: added encoder support for end of stream
handling").
> 
> > +	  </row>
> >   	</tbody>
> >         </tgroup>
> >       </table>
> > diff --git a/Documentation/DocBook/media/v4l/vidioc-qbuf.xml b/Documentation/DocBook/media/v4l/vidioc-qbuf.xml
> > index 9caa49a..ad49f7d 100644
> > --- a/Documentation/DocBook/media/v4l/vidioc-qbuf.xml
> > +++ b/Documentation/DocBook/media/v4l/vidioc-qbuf.xml
> > @@ -76,6 +76,8 @@ supports capturing from specific video inputs and you want to specify a video
> >   input, then <structfield>flags</structfield> should be set to
> >   <constant>V4L2_BUF_FLAG_INPUT</constant> and the field
> >   <structfield>input</structfield> must be initialized to the desired input.
> > +Some drivers expects applications set <constant>V4L2_BUF_FLAG_EOS</constant>
> > +flag on the last buffer of the stream.
> >   The <structfield>reserved</structfield> field must be set to 0. When using
> >   the <link linkend="planar-apis">multi-planar API</link>, the
> >   <structfield>m.planes</structfield> field must contain a userspace pointer
> > diff --git a/include/linux/videodev2.h b/include/linux/videodev2.h
> > index 370d111..e44a7cd 100644
> > --- a/include/linux/videodev2.h
> > +++ b/include/linux/videodev2.h
> > @@ -676,6 +676,7 @@ struct v4l2_buffer {
> >   /* Cache handling flags */
> >   #define V4L2_BUF_FLAG_NO_CACHE_INVALIDATE	0x0800
> >   #define V4L2_BUF_FLAG_NO_CACHE_CLEAN		0x1000
> > +#define V4L2_BUF_FLAG_EOS	0x2000	/* The last buffer in the stream */
> >   
> >   /*
> >    *	O V E R L A Y   P R E V I E W
> > 
> 
> 
Regards
Andrzej