USB C dock - hdmi adventure

[NO_ob]

I did the cc fix (removed two switches on the motherboard) on my PP BH in order to enable USB OTG and hdmi output. Booting the recent factory image flashed new firmware and ran tests just fine indicating I did not destroy anything in the process. I hooked up my cheap USB C hub and mouse and keyboards works fine. Oh how lovely it is to use the terminal with a physical keyboard! The hub even charges the PP while connected. 

Hdmi output did not "just work" and I need help with it. I got Mobian on emmc which requires (according to the mobian wiki) the internal screen to be disabled in order to get hdmi out working. My goal is to extend the desktop like on Martijn´s convergence video. So I booted Danct12´s Arch (Thank you @Danct12 for your hard work!) from sd card and installed wlr-randr. With the monitor attached it gives this output:



The monitor (HDMI-A-1 Asus VG249) is recognized and is enabled (I can move the mouse to the right as if I´m moving it over to the Asus monitor) but the monitor says No signal. I have tried a few different refresh rates and resolutions that is supported according to wlr-randr but still no sight of life on the Asus monitor. It does however wake up when I attach the hdmi cable so there is some connection. Disabling the internal (DSI-1) display have worked for some people but since I don´t have ssh I argue that I need the display on the PP. 

If someone have had success making both internal and external displays working like in Martijn´s video, please share how you did it. And if someone has any questions for me, please ask!

EDIT: I tried with my TV as well, but its the same thing. TV is enabled but shows No signal.



EDIT2: Success! Setting 1280x720@50Hz enabled the external monitor! The result seems very random though because trying again with the same settings did not work. Reboot, fiddle, then it worked again. Until the phone froze that is. Non the less, this is a success and proof that it actually works! I have a video but cant upload it to the forum.



Video showing internal and external screens enabled:
https://youtu.be/x9klL7PyvS0

It might be worth trying out gnome, you can install gdm and gnome then do "systemctl disable phosh" and "systemctl enable gdm" then reboot and login to a gnome desktop, I assume the second monitor will just work from there, to get back to phosh you can either re enable it and disable gdm or select phosh from the gdm login screen