Hi Hans,

On 1/8/20 6:09 PM, Hans Verkuil wrote:

On 1/6/20 4:49 PM, Stanimir Varbanov wrote:

quoted

This event indicate that the source color bit-depth is changed
during run-time. The client must get the new format and re-allocate
buffers for it. This can usually happens with video decoder (encoders)
when the bit-stream color bit-depth is changed from 8 to 10bits
or vice versa.

Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Stanimir Varbanov <redacted>
---
 Documentation/media/uapi/v4l/vidioc-dqevent.rst | 8 +++++++-
 Documentation/media/videodev2.h.rst.exceptions  | 1 +
 include/uapi/linux/videodev2.h                  | 1 +
 3 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/Documentation/media/uapi/v4l/vidioc-dqevent.rst b/Documentation/media/uapi/v4l/vidioc-dqevent.rst
index 42659a3d1705..fad853d440cf 100644
--- a/Documentation/media/uapi/v4l/vidioc-dqevent.rst
+++ b/Documentation/media/uapi/v4l/vidioc-dqevent.rst

@@ -402,7 +402,13 @@ call.
 	that many Video Capture devices are not able to recover from a temporary
 	loss of signal and so restarting streaming I/O is required in order for
 	the hardware to synchronize to the video signal.
-
+    * - ``V4L2_EVENT_SRC_CH_COLOR_DEPTH``
+      - 0x0002
+      - This event gets triggered when color bit-depth change is detected
+	from a video decoder. Applications will have to query the new pixel
+	format and re-negotiate the queue. In most cases the streaming must be
+	stopped and restarted (:ref:`VIDIOC_STREAMOFF <VIDIOC_STREAMON>`
+	followed by :ref:`VIDIOC_STREAMON <VIDIOC_STREAMON>`).

I think this is too specific for decoders. Something similar to the
CH_RESOLUTION description would be more appropriate:

      - This event gets triggered when a color bit-depth change (but not a
	resolution change!) is detected	at an input. This can come from an

What you mean by "but not a resolution change" here? Resolution change
and bit-depth change cannot occur on the same time, or something else.

I would say that for Venus (and probably others) on initialization time
both could be changed on the same time, because we cannot predict the
resolution and bit-depth before parsing bitstream headers.

	input connector or from a video decoder. Applications will have to query
	the new pixel format and re-negotiate the queue.

	For stateful decoders follow the guidelines in :ref:`decoder`.
	Video capture devices will in most cases have to stop and restart
	streaming (:ref:`VIDIOC_STREAMOFF <VIDIOC_STREAMON>` followed by
	:ref:`VIDIOC_STREAMON <VIDIOC_STREAMON>`).

And update dev-decoder.rst where needed with this new event flag.

As to your question on irc: once I've acked this patch it can be merged
via a venus PR.

Regards,

	Hans

quoted

 
 Return Value
 ============

diff --git a/Documentation/media/videodev2.h.rst.exceptions b/Documentation/media/videodev2.h.rst.exceptions
index cb6ccf91776e..209709114378 100644
--- a/Documentation/media/videodev2.h.rst.exceptions
+++ b/Documentation/media/videodev2.h.rst.exceptions

@@ -490,6 +490,7 @@ replace define V4L2_EVENT_CTRL_CH_FLAGS ctrl-changes-flags
 replace define V4L2_EVENT_CTRL_CH_RANGE ctrl-changes-flags
 
 replace define V4L2_EVENT_SRC_CH_RESOLUTION src-changes-flags
+replace define V4L2_EVENT_SRC_CH_COLOR_DEPTH src-changes-flags
 
 replace define V4L2_EVENT_MD_FL_HAVE_FRAME_SEQ :c:type:`v4l2_event_motion_det`
 

diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
index 5f9357dcb060..1d349c9d57a7 100644
--- a/include/uapi/linux/videodev2.h
+++ b/include/uapi/linux/videodev2.h

@@ -2332,6 +2332,7 @@ struct v4l2_event_frame_sync {
 };
 
 #define V4L2_EVENT_SRC_CH_RESOLUTION		(1 << 0)
+#define V4L2_EVENT_SRC_CH_COLOR_DEPTH		(1 << 1)
 
 struct v4l2_event_src_change {
 	__u32 changes;

-- 
regards,
Stan