From 1611c686c1245408c3ddb451b2a5fff1dc088d6e Mon Sep 17 00:00:00 2001 From: Hans Verkuil Date: Mon, 17 Sep 2018 07:37:18 -0400 Subject: [PATCH] media: vidioc-dqevent.rst: clarify V4L2_EVENT_SRC_CH_RESOLUTION Clarify that when you receive V4L2_EVENT_SOURCE_CHANGE with flag V4L2_EVENT_SRC_CH_RESOLUTION set, and the new resolution appears identical to the old resolution, then you still must restart the streaming I/O. Signed-off-by: Hans Verkuil Acked-by: Sakari Ailus Signed-off-by: Hans Verkuil Signed-off-by: Mauro Carvalho Chehab --- Documentation/media/uapi/v4l/vidioc-dqevent.rst | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/Documentation/media/uapi/v4l/vidioc-dqevent.rst b/Documentation/media/uapi/v4l/vidioc-dqevent.rst index cb3565f36793..04416b6943c0 100644 --- a/Documentation/media/uapi/v4l/vidioc-dqevent.rst +++ b/Documentation/media/uapi/v4l/vidioc-dqevent.rst @@ -379,7 +379,17 @@ call. - 0x0001 - 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. + decoder. Applications will have to query the new resolution (if + any, the signal may also have been lost). + + *Important*: even if the new video timings appear identical to the old + ones, receiving this event indicates that there was an issue with the + video signal and you must stop and restart streaming + (:ref:`VIDIOC_STREAMOFF ` + followed by :ref:`VIDIOC_STREAMON `). The reason is + that many 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. Return Value -- 2.45.2