Hello storz,
I wonder if you ever managed to get this to work. I used to have this working, but not anymore, and I wonder if I can make it work again.
I have an Anker A8312 USB-C to HDMI adapter (which, like all similar adapters, really does DisplayPort in Alt mode over USB-C, and from there converts to HDMI). I previously used this on my PBP with Armbian Focal, and it worked fine just so long as I ran GNOME on X.org, as opposed to Wayland. I was able to connect an external monitor via an HDMI cable, it showed up in the GNOME display settings, and I was able to use it as one would expect. I unfortunately have a hard time finding out the exact kernel version I used at the time, but I believe it was a 4.9 rockchip kernel.
I recently reinstalled my PBP using Armbian Noble and apparently there's a kernel regression that causes the adapter to not be recognised anymore. On a 6.1 kernel (which is what shipped with Armbian Noble as it came out), the device is not recognised at all. On a 6.12 kernel (currently available via updates, at the time of writing), the device does show up in lsusb, but only as a "billboard device" which means that the device wasn't correctly switched into DP Alt mode and is thus unusable for connecting a screen. I am still on GNOME on X.org, I still use the same adapter, and I still connect to the same monitor with the same cable as before. So with all other variables being identical, I do strongly suspect this to be a kernel or perhaps a firmware issue.
Perhaps you (or someone else) have any pointers that might help me move towards getting this working again. I'd be most grateful for those. Thanks!
Cheers,
Florian
