Okay, like you guys I have been messing with this. I am pretty sure at this point it takes a few pieces to make this work that haven’t been documented – at least that I can find. Those would include:
- Changes to uboot (recompile) to have it initialize mDP port (no documentation on how to build for your self that I can find)
- Update to DTB to match one used in Raxda image
- Linux DP display driver being included in kernel
- Firmware file as mentioned in previous comment
It would appear that someone took their time putting together the images
rockpi4c_debian_stretch_desktop_arm64_20200716_0647-gpt.img.gz and Android 10 to include these tweaks so mDP works, but didn’t document it anywhere so that it can be replicated into newer images. I know that Armbian has a few people, including my self trying to get it working, though, so hopefully something available on that front here soon.
It is CNY now so I am sure official responses will be slow, though hopefully after the holidays if Armbian hasn’t figured this out we can convince someone over there at Raxda to give us a hand.
To note, I have had mixed success with mini-dp adapters. I have had the most success with mini-DP to VGA adapters while I have so far tested 1 mini-DP to HDMI that has “worked” but flickered on and off constantly. I have another adapter on the way to test as well. Of course, this is only with the Raxda provided image for Debian / Android where it has worked at all.
If anyone is interested in the adapters I have tested specifically, reply and let me know and I can provide them / links.
my 2 cents.