@tkaiser Here are some info recently from radxa:
Radxa is trying to do PD negotiation in u-boot. Some codes are already pushed:https://github.com/radxa/u-boot/commits/stable-5.10-rock5.
PD negotiation in u-boot makes things better because it’s far earlier than the negotiation in kernel after the power is pulgged into the typec port. Because of the low speed of tf card, when the kernel starts to negotiate with the PD source, the PD source is in a timeout state and then hard reset, which means power down. I’ve tested the new u-boot, which will make the system on tf card boot up. There are still some power down during the boot process but I think that is software issue. And radxa is now working on it.
I like the full-featured typec, and I’ve been testing it many times to get closer to the root cause of the PD related issues. And I believe radxa will finally get these things done.