DM385 ISP VDINT interrupt while no VS input

Hello.

I use DM385 to capture YUV 422 image from camera interface.

I found something strange.

I capture YUV 422 image for some frames,and then keep VS low ,send HS for ever.

I found the ISP get VDINT interrupt 3 times for a second.

The first some frames timing is :

If I keep VS low ,send HS for ever,the new timing is :

  I set ISP VDPOL is 1.

 In my opinion,I keep VS low,and the ISP will not get VDINT interrupt again.

 I use IPNC RDK 3.8.And I found the same thing in IPNC RDK 3.5.