Hi again,
I can also confirm that the behavior of this hdmi output depends also on the version of uboot. I have been playing around with at least two of them. With one of them everything works (with this old 5.7 kernel), with the other one, it worked pretty badly and even ending with this blinking green and red light.
Hope that could help…
alex
…does not work with 5.19 branch too…
I have been playing this kernel change game as well trying to get the usb-c to hdmi to work again after re-flashing the emmc from the original Manjaro KDE that came loaded on the PBPRO back in 2020. I decided to dump KDE recently and try out the XFCE Manjaro image. And of course that broke the hdmi out. HDMI used to work just fine with any usb-c to hdmi adpter on the Manjaro image with Kernel 5.7. Now, the current Manjaro images available on Github all come with kernel 5.18 and hdmi doesn't work. And if you update to the latest 5.19.11 is still broken.
However, there is a difference in kernel images "linux 5.18" and "linux-pinebookpro 5.7". The Manjaro repo still have the "linux-pinebookpro" image which is the 5.7 and usb-c to hdmi works, but unfortunately for me I deal with another issue related to the panel-simple/panel-edp module which makes the system boot up into a black screen at least 9 out of 10 times. So I am out of luck with Manjaro for now until they fix the usb-c to hdmi issue hopefully in kernel 6?
I've played around with other distro images as well (Armbian, TwisterOS and Kali) and found out that TwisterOS comes with kernel 5.10 and hdmi works fine. Armbian and Kali are also broken with the LTS kernel 5.15.
It would be nice to get the Manjaro team to upload the original images with kernel 5.7 to their Github page.