Hi anjo
You might have to look the kernel config CONFIG_VIDEO_ADV_DEBUG and VIDEO_ADV_DEBUG
Also if you are with Yocto, utilities on v4l-utils and v4l2-dbg: allows access to DBG_G_CHIP_INFO, DBG_G/S_REGISTER
Core debugging: 'echo 1 >/sys/class/video4linux/video0/debug'.
1: show ioctl name
2: show arguments as well
Hope this helps