Em 18-06-2012 08:54, Andrzej Hajda escreveu:
> 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@xxxxxxxxxxx>
>>> Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
>>> ---
>>> 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").
So?
The point is: new changes should not break backward compatibility,
otherwise a regression is introduced, and such patch should be nacked.
So, newer functionality should carefully be introduced in a way that it
won't make older apps to break.
That means that you'll need to work on some design that an EOS flag will
be used only if the application is known to be compiled with EOS flag support.
Regards,
Mauro
>>
>>> + </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
>
>
--
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
