Hi Arun,

I've got some more comments w.r.t. the documentation:

On 05/13/14 07:59, Arun Kumar K wrote:
> This event indicates that the video device has encountered
> a source parameter change during runtime. This can typically be a
> resolution change detected by a video decoder OR a format change
> detected by an HDMI connector.
> 
> This needs to be nofified to the userspace and the application may
> be expected to reallocate buffers before proceeding. The application
> can subscribe to events on a specific pad or input port which
> it is interested in.
> 
> Signed-off-by: Arun Kumar K <arun...@samsung.com>
> ---
>  Documentation/DocBook/media/v4l/vidioc-dqevent.xml |   32 +++++++++++++++++
>  .../DocBook/media/v4l/vidioc-subscribe-event.xml   |   19 +++++++++++
>  drivers/media/v4l2-core/v4l2-event.c               |   36 
> ++++++++++++++++++++
>  include/media/v4l2-event.h                         |    4 +++
>  include/uapi/linux/videodev2.h                     |    8 +++++
>  5 files changed, 99 insertions(+)
> 
> diff --git a/Documentation/DocBook/media/v4l/vidioc-dqevent.xml 
> b/Documentation/DocBook/media/v4l/vidioc-dqevent.xml
> index 89891ad..6afabaa 100644
> --- a/Documentation/DocBook/media/v4l/vidioc-dqevent.xml
> +++ b/Documentation/DocBook/media/v4l/vidioc-dqevent.xml
> @@ -242,6 +242,22 @@
>        </tgroup>
>      </table>
>  
> +    <table frame="none" pgwide="1" id="v4l2-event-src-change">
> +      <title>struct <structname>v4l2_event_src_change</structname></title>
> +      <tgroup cols="3">
> +     &cs-str;
> +     <tbody valign="top">
> +       <row>
> +         <entry>__u32</entry>
> +         <entry><structfield>changes</structfield></entry>
> +         <entry>
> +           A bitmask that tells what has changed. See <xref 
> linkend="src-changes-flags" />.
> +         </entry>
> +       </row>
> +     </tbody>
> +      </tgroup>
> +    </table>
> +
>      <table pgwide="1" frame="none" id="changes-flags">
>        <title>Changes</title>
>        <tgroup cols="3">
> @@ -270,6 +286,22 @@
>       </tbody>
>        </tgroup>
>      </table>
> +
> +    <table pgwide="1" frame="none" id="src-changes-flags">
> +      <title>Source Changes</title>
> +      <tgroup cols="3">
> +     &cs-def;
> +     <tbody valign="top">
> +       <row>
> +         <entry><constant>V4L2_EVENT_SRC_CH_RESOLUTION</constant></entry>
> +         <entry>0x0001</entry>
> +         <entry>This event gets triggered when a resolution change is
> +         detected at runtime. This can typically come from a video decoder.

I would rewrite this as:

"This event gets triggered when a resolution change is detected at an input.
This can come from an input connector or from a video decoder."

> +         </entry>
> +       </row>
> +     </tbody>
> +      </tgroup>
> +    </table>
>    </refsect1>
>    <refsect1>
>      &return-value;
> diff --git a/Documentation/DocBook/media/v4l/vidioc-subscribe-event.xml 
> b/Documentation/DocBook/media/v4l/vidioc-subscribe-event.xml
> index 5c70b61..067a0d5 100644
> --- a/Documentation/DocBook/media/v4l/vidioc-subscribe-event.xml
> +++ b/Documentation/DocBook/media/v4l/vidioc-subscribe-event.xml
> @@ -155,6 +155,25 @@
>           </entry>
>         </row>
>         <row>
> +         <entry><constant>V4L2_EVENT_SOURCE_CHANGE</constant></entry>
> +         <entry>5</entry>
> +         <entry>
> +           <para>This event is triggered when a source parameter change is
> +            detected during runtime by the video device. It can be a
> +            runtime resolution change triggered by a video decoder or the
> +            format change happening on an HDMI connector.

s/an HDMI/an input/

It's valid for e.g. a composite input as well (or DVI, or VGA, etc.)

> +            This event requires that the <structfield>id</structfield>
> +            matches the pad / input index from which you want to receive

This should be more explicit:

"matches the input index (when used with a video device node) or the pad
index (when used with a subdevice node) from which you want to receive"

> +            events.</para>
> +              <para>This event has a &v4l2-event-source-change; associated
> +           with it. The <structfield>changes</structfield> bitfield denotes
> +           what has changed for the subscribed pad. If multiple events
> +           occured before application could dequeue them, then the changes

s/occured/occurred/

> +           will have the ORed value of all the events generated.</para>
> +         </entry>
> +       </row>
> +       <row>
>           <entry><constant>V4L2_EVENT_PRIVATE_START</constant></entry>
>           <entry>0x08000000</entry>
>           <entry>Base event number for driver-private events.</entry>
> diff --git a/drivers/media/v4l2-core/v4l2-event.c 
> b/drivers/media/v4l2-core/v4l2-event.c
> index 86dcb54..8761aab 100644
> --- a/drivers/media/v4l2-core/v4l2-event.c
> +++ b/drivers/media/v4l2-core/v4l2-event.c
> @@ -318,3 +318,39 @@ int v4l2_event_subdev_unsubscribe(struct v4l2_subdev 
> *sd, struct v4l2_fh *fh,
>       return v4l2_event_unsubscribe(fh, sub);
>  }
>  EXPORT_SYMBOL_GPL(v4l2_event_subdev_unsubscribe);
> +
> +static void v4l2_event_src_replace(struct v4l2_event *old,
> +                             const struct v4l2_event *new)
> +{
> +     u32 old_changes = old->u.src_change.changes;
> +
> +     old->u.src_change = new->u.src_change;
> +     old->u.src_change.changes |= old_changes;
> +}
> +
> +static void v4l2_event_src_merge(const struct v4l2_event *old,
> +                             struct v4l2_event *new)
> +{
> +     new->u.src_change.changes |= old->u.src_change.changes;
> +}
> +
> +static const struct v4l2_subscribed_event_ops v4l2_event_src_ch_ops = {
> +     .replace = v4l2_event_src_replace,
> +     .merge = v4l2_event_src_merge,
> +};
> +
> +int v4l2_src_change_event_subscribe(struct v4l2_fh *fh,
> +                             const struct v4l2_event_subscription *sub)
> +{
> +     if (sub->type == V4L2_EVENT_SOURCE_CHANGE)
> +             return v4l2_event_subscribe(fh, sub, 0, &v4l2_event_src_ch_ops);
> +     return -EINVAL;
> +}
> +EXPORT_SYMBOL_GPL(v4l2_src_change_event_subscribe);
> +
> +int v4l2_src_change_event_subdev_subscribe(struct v4l2_subdev *sd,
> +             struct v4l2_fh *fh, struct v4l2_event_subscription *sub)
> +{
> +     return v4l2_src_change_event_subscribe(fh, sub);
> +}
> +EXPORT_SYMBOL_GPL(v4l2_src_change_event_subdev_subscribe);
> diff --git a/include/media/v4l2-event.h b/include/media/v4l2-event.h
> index be05d01..1ab9045 100644
> --- a/include/media/v4l2-event.h
> +++ b/include/media/v4l2-event.h
> @@ -132,4 +132,8 @@ int v4l2_event_unsubscribe(struct v4l2_fh *fh,
>  void v4l2_event_unsubscribe_all(struct v4l2_fh *fh);
>  int v4l2_event_subdev_unsubscribe(struct v4l2_subdev *sd, struct v4l2_fh *fh,
>                                 struct v4l2_event_subscription *sub);
> +int v4l2_src_change_event_subscribe(struct v4l2_fh *fh,
> +                             const struct v4l2_event_subscription *sub);
> +int v4l2_src_change_event_subdev_subscribe(struct v4l2_subdev *sd,
> +             struct v4l2_fh *fh, struct v4l2_event_subscription *sub);
>  #endif /* V4L2_EVENT_H */
> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
> index ea468ee..b923d91 100644
> --- a/include/uapi/linux/videodev2.h
> +++ b/include/uapi/linux/videodev2.h
> @@ -1765,6 +1765,7 @@ struct v4l2_streamparm {
>  #define V4L2_EVENT_EOS                               2
>  #define V4L2_EVENT_CTRL                              3
>  #define V4L2_EVENT_FRAME_SYNC                        4
> +#define V4L2_EVENT_SOURCE_CHANGE             5
>  #define V4L2_EVENT_PRIVATE_START             0x08000000
>  
>  /* Payload for V4L2_EVENT_VSYNC */
> @@ -1796,12 +1797,19 @@ struct v4l2_event_frame_sync {
>       __u32 frame_sequence;
>  };
>  
> +#define V4L2_EVENT_SRC_CH_RESOLUTION         (1 << 0)
> +
> +struct v4l2_event_src_change {
> +     __u32 changes;
> +};
> +
>  struct v4l2_event {
>       __u32                           type;
>       union {
>               struct v4l2_event_vsync         vsync;
>               struct v4l2_event_ctrl          ctrl;
>               struct v4l2_event_frame_sync    frame_sync;
> +             struct v4l2_event_src_change    src_change;
>               __u8                            data[64];
>       } u;
>       __u32                           pending;
> 

Regards,

        Hans
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