pxp_v4l2_test program without output on LCD display


I have imx6ul dev board. I also compiled imx_test-5.7. In the test package, there is a program pxp_v4l2_test.out under the unit_tests folder. I run :

pxp_v4l2_test.out -sx 350 -sy 240 -res 350:240 -dst 0:0:350:240 -a 100 -a 100 -w 5 t_yuv420_il.yuv BLANK

The program output:

unable to open /dev/video for output, continue searching device.
Found v4l2 output device /dev/video0.
V4L output 0 (0x8e100000): PxP Display Output
Video input format: 350x240 YUV 4:2:0 Planar
request count 6
win.w.l/t/w/h = 0/0/350/240
crop.c.l/t/w/h = 0/0/350/240
PxP processing: start…
total time for 1 frames = 2500 us, 400 fps
VIDIOC_STREAMOFF: Invalid argument

From the document:

Expected Result | The video streaming can be viewed on LCD.

But there is no image or video displayed on the LCD.

I also installed gstreamer. it can play back a video clip onto the v4l2sink, and video clip is successfully rendered onto the LCD screen.

For the pxp_v4l2_test.out, what is missing?

Thank you,