Hikey970 and usb camera

Hello everybody
I have try to connect a camera on the hikey970 board . Under linux it’s works perfectly but under android the camera is detect by the linux kernel but the android systéme doesn’t seems to use it.

//get the camera manager
CameraManager manager = (CameraManager) this.getSystemService(Context.CAMERA_SERVICE);
for (String cameraId : manager.getCameraIdList()) {
//The android camera list is empty…

any ideas