[PATCH 1/2 v2] v4l: soc-camera: start stream after queueing the buffers

Anatolij Gustschin agust at denx.de
Mon Jan 31 07:19:32 EST 2011

Some camera systems have strong requirement for capturing
an exact number of frames after starting the stream and do
not tolerate losing captured frames. By starting the stream
after the videobuf has queued the buffers, we ensure that
no frame will be lost.

Signed-off-by: Anatolij Gustschin <agust at denx.de>
    Check for return value of videobuf_streamon() before
    starting the stream, as suggested by Guennadi.

 drivers/media/video/soc_camera.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/media/video/soc_camera.c b/drivers/media/video/soc_camera.c
index a66811b..e09bec0 100644
--- a/drivers/media/video/soc_camera.c
+++ b/drivers/media/video/soc_camera.c
@@ -646,11 +646,12 @@ static int soc_camera_streamon(struct file *file, void *priv,
 	if (icd->streamer != file)
 		return -EBUSY;
-	v4l2_subdev_call(sd, video, s_stream, 1);
 	/* This calls buf_queue from host driver's videobuf_queue_ops */
 	ret = videobuf_streamon(&icd->vb_vidq);
+	if (!ret)
+		v4l2_subdev_call(sd, video, s_stream, 1);
 	return ret;

More information about the linux-arm-kernel mailing list