Define a frame start event to tell user space when the reception of a frame
starts.
Signed-off-by: Sakari Ailus <sakari.ai...@iki.fi>
---
Documentation/DocBook/media/v4l/vidioc-dqevent.xml | 26 ++++++++++++++++++++
.../DocBook/media/v4l/vidioc-subscribe-event.xml | 18 +++++++++++++
include/linux/videodev2.h | 12 +++++++--
3 files changed, 53 insertions(+), 3 deletions(-)
diff --git a/Documentation/DocBook/media/v4l/vidioc-dqevent.xml
b/Documentation/DocBook/media/v4l/vidioc-dqevent.xml
index 5200b68..d2cb8db 100644
--- a/Documentation/DocBook/media/v4l/vidioc-dqevent.xml
+++ b/Documentation/DocBook/media/v4l/vidioc-dqevent.xml
@@ -88,6 +88,12 @@
</row>
<row>
<entry></entry>
+ <entry>&v4l2-event-frame-sync;</entry>
+ <entry><structfield>frame</structfield></entry>
+ <entry>Event data for event V4L2_EVENT_FRAME_START.</entry>
+ </row>
+ <row>
+ <entry></entry>
<entry>__u8</entry>
<entry><structfield>data</structfield>[64]</entry>
<entry>Event data. Defined by the event type. The union
@@ -220,6 +226,26 @@
</tgroup>
</table>
+ <table frame="none" pgwide="1" id="v4l2-event-frame-sync">
+ <title>struct <structname>v4l2_event_frame_sync</structname></title>
+ <tgroup cols="3">
+ &cs-str;
+ <tbody valign="top">
+ <row>
+ <entry>__u32</entry>
+ <entry><structfield>buffer_sequence</structfield></entry>
+ <entry>
+ The sequence number of the buffer to be handled next or
+ currently handled by the driver.
+ </entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+
+ <para>&v4l2-event-frame-sync; is associated with
+ <constant>V4L2_EVENT_FRAME_START</constant> event.</para>
+
<table pgwide="1" frame="none" id="changes-flags">
<title>Changes</title>
<tgroup cols="3">
diff --git a/Documentation/DocBook/media/v4l/vidioc-subscribe-event.xml
b/Documentation/DocBook/media/v4l/vidioc-subscribe-event.xml
index 275be96..7ec42bb 100644
--- a/Documentation/DocBook/media/v4l/vidioc-subscribe-event.xml
+++ b/Documentation/DocBook/media/v4l/vidioc-subscribe-event.xml
@@ -139,6 +139,24 @@
</entry>
</row>
<row>
+ <entry><constant>V4L2_EVENT_FRAME_START</constant></entry>
+ <entry>4</entry>
+ <entry>
+ <para>Triggered immediately when the reception of a
+ frame has begun. This event has a
+ &v4l2-event-frame-sync; associated with it.</para>
+
+ <para>A driver will only generate this event when the
+ hardware can generate it. This might not be the case
+ e.g. when the hardware has no DMA buffer to write the
+ image data to. In such cases the
+ <structfield>buffer_sequence</structfield> field in
+ &v4l2-event-frame-sync; will not be incremented either.
+ This causes two consecutive buffer sequence numbers to
+ have n times frame interval in between them.</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/linux/videodev2.h b/include/linux/videodev2.h
index fca24cc..4265102 100644
--- a/include/linux/videodev2.h
+++ b/include/linux/videodev2.h
@@ -2006,6 +2006,7 @@ struct v4l2_streamparm {
#define V4L2_EVENT_VSYNC 1
#define V4L2_EVENT_EOS 2
#define V4L2_EVENT_CTRL 3
+#define V4L2_EVENT_FRAME_START 4
#define V4L2_EVENT_PRIVATE_START 0x08000000
/* Payload for V4L2_EVENT_VSYNC */
@@ -2032,12 +2033,17 @@ struct v4l2_event_ctrl {
__s32 default_value;
};
+struct v4l2_event_frame_sync {
+ __u32 buffer_sequence;
+};
+
struct v4l2_event {
__u32 type;
union {
- struct v4l2_event_vsync vsync;
- struct v4l2_event_ctrl ctrl;
- __u8 data[64];
+ struct v4l2_event_vsync vsync;
+ struct v4l2_event_ctrl ctrl;
+ struct v4l2_event_frame_sync frame_sync;
+ __u8 data[64];
} u;
__u32 pending;
__u32 sequence;
--
1.7.2.5
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