Jeston Tk1 use qt+gstreamer v4l2src: "device busy" error when setting to READY and back to

hi:
I’m in Jeston Tk1 ust qt+gstramer to record and preview camera use v4l2src element, When setting Pipeline for the GST_MESSAGE_READY state of the V4L2SRC element to stop the video, I give a PLAY state again ,The V4L2 element display the “busy device” error, please tell me how to solve this problem, thank you very much
https://bugzilla.gnome.org/show_bug.cgi?id=770308 is my bug info
gstreamer reply:
Olivier Crête [developer] 2016-08-24 15:49:03 UTC
In my experience, the NVidia Tegra kernel drivers are particularly crappy, so if you want to use that platform, you must either be ready to invest in fixing their kernel, or you must be ready to work around all kind of bugs they have.
please help me, thank you very much.

There is no any particulary crappy for the Tegra kernel drivers if you are using the usb camera (UVC). Could you give more detail information like BSP version.

I can get the preview by below command by the r21.4 release BSP.
gst-launch-1.0 v4l2src device="/dev/video0" ! “video/x-raw, width=640, height=480, format=(string)I420” ! nvhdmioverlaysink -e