I'm quite sure this is (was) a bug because I fixed it Here's howto. I'd like to provide (attach here) the overlay dts / dtbo but that doesnt seem to be possible or allowed here?!
the built overlay-ov5640.dts has been derieved from an OrangePi One H3 and power pin GPIOs adjusted / removed then compiled into dtbo
compile and copy the overlay
dtc -I dts -O dtb -o overlay-ov5640.dtbo overlay-ov5640.dts
cp /root/overlay-ov5640.dtbo /boot/dtb/overlay/sun8i-h3-ov5640.dtbo
finally the boot env has been adjusted
add the ov5640 to the "overlays" list. Note that the copied file above follows the naming conventions like the others.
overlays=i2c0 i2c1 i2c2 usbhost0 usbhost2 usbhost3 ov5640
after reboot one should have now a /dev/video1 and /dev/media1 device.
Note that /dev/video0 still seems to be the cedrus decoder only (not yet further investigated)
Note that the overlay enables the Pullups on i2c2 which isn't necessary on the NanoPi Duo2 because it has 1k on board as per schematics but it doesnt hurt.
mjpeg_streamer works with some parameter tweaking.
ffmpeg works as well but needs lots of more parameter tuning.
Next story is to get hardware acceleration working (cedrus) ideally for encoding and decoding h264.