Strange issue with builtin webcam

Hi experts.

Could you please guide me on webcam ? My HP laptop has inbuilt webcam and below is dmesg o/p

usb 1-4: Found UVC 1.00 device HP TrueVision HD Camera (05c8:03d2)
[    9.424351] input: HP TrueVision HD Camera: HP Tru as /devices/pci0000:00/0000:00:08.1/0000:04:00.3/usb1/1-4/1-4:1.0/input/input17

After reboot, The Sudo can detect the webcam device first time

sudo v4l2-ctl --list-devices
[sudo] password for compu: 
HP TrueVision HD Camera: HP Tru (usb-0000:04:00.3-4):

But, executing the commend next time, no more able to see any video device afterwards.

sudo v4l2-ctl --list-devices
Cannot open device /dev/video0, exiting.

As a result , guvcview , chesse all are reporting ( even with sudo) no v4l2 device found.

This behavior raise two question.

  1. How to get the video devices stay
  2. How to access video device as non admin. We can add user in video group, but these days udev take care the ACL, so interested to follow the same track for persistence.

Thanks in advanced for your time.