Hi Laurent,
Thank you for the review.
On Mon, Apr 21, 2014 at 3:54 PM, Laurent Pinchart
<laurent.pinchart@xxxxxxxxxxxxxxxx> wrote:
> Hi Arun,
>
> Thank you for the patch.
>
> On Monday 21 April 2014 14:56:01 Arun Kumar K wrote:
>> From: Pawel Osciak <posciak@xxxxxxxxxxxx>
>>
>> This event indicates that the decoder has reached a point in the stream,
>> at which the resolution changes. The userspace is expected to provide a new
>> set of CAPTURE buffers for the new format before decoding can continue.
>> The event can also be used for more generic events involving resolution
>> or format changes at runtime for all kinds of video devices.
>>
>> Signed-off-by: Pawel Osciak <posciak@xxxxxxxxxxxx>
>> Signed-off-by: Arun Kumar K <arun.kk@xxxxxxxxxxx>
>> ---
>> .../DocBook/media/v4l/vidioc-subscribe-event.xml | 16 ++++++++++++++++
>> include/uapi/linux/videodev2.h | 6 ++++++
>> 2 files changed, 22 insertions(+)
>>
>> diff --git a/Documentation/DocBook/media/v4l/vidioc-subscribe-event.xml
>> b/Documentation/DocBook/media/v4l/vidioc-subscribe-event.xml index
>> 5c70b61..0aec831 100644
>> --- a/Documentation/DocBook/media/v4l/vidioc-subscribe-event.xml
>> +++ b/Documentation/DocBook/media/v4l/vidioc-subscribe-event.xml
>> @@ -155,6 +155,22 @@
>> </entry>
>> </row>
>> <row>
>> + <entry><constant>V4L2_EVENT_SOURCE_CHANGE</constant></entry>
>> + <entry>5</entry>
>> + <entry>
>> + <para>This event is triggered when a resolution or format 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. Application may
>> + need to reinitialize buffers before proceeding further.</para>
>> +
>> + <para>This event has a &v4l2-event-source-change; associated
>> + with it. This has significance only for v4l2 subdevs where the
>> + <structfield>pad_num</structfield> field will be updated with
>> + the pad number on which the event is triggered.</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/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
>> index 6ae7bbe..12e0614 100644
>> --- a/include/uapi/linux/videodev2.h
>> +++ b/include/uapi/linux/videodev2.h
>> @@ -1733,6 +1733,7 @@ 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 */
>> @@ -1764,12 +1765,17 @@ struct v4l2_event_frame_sync {
>> __u32 frame_sequence;
>> };
>>
>> +struct v4l2_event_source_change {
>> + __u32 pad_num;
>
> I would call the field just "pad",
>
Ok.
>> +};
>> +
>> 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_source_change source_change;
>> __u8 data[64];
>
> This looks pretty good to me, but I'm a bit concerned about future
> compatibility. We might need to report more information to userspace, and in
> particular what has been changed at the source (resolution, format, ...). In
> order to do so, we'll need to add a flag field to v4l2_event_source_change.
Ok a flag can be added with bitfields for reporting specific event type.
> The next __u32 right after the source_change field must thus be zeroed. I see
> two ways of doing so:
>
> - zeroing the whole data array before setting event-specific data
> - adding a reserved must-be-zeroed field to v4l2_event_source_change
>
> I like the former better as it's more generic, but we then need to ensure that
> all drivers zero the whole data field correctly. Adding a new
> v4l2_event_init() function would help with that.
>
Is that a good idea to have an init() function just for zeroing the data field?
If this is agreed upon, I can add this, but it can be easily missed
out by drivers.
Also how about the drivers already using the v4l2_event. Should we
update those drivers too with v4l2_event_init() ?
Regards
Arun
>> } u;
>> __u32 pending;
>
> --
> Regards,
>
> Laurent Pinchart
>
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