2021–11–05:
Pinephone Pro – USB, Type-C, OTG, DP-Alt mode, Charger,…
I've been looking at how all this works on Rockchip platform and in the
mainline kernel for the last few weeks, writing docs, making diagrams, … and
I've come up with a solution to tying together all the 7 or so drivers that
need to communicate to make this all work.
This should end up being better than the incomplete solution
that's currently available on Pinephone Pro or Pinebook Pro.
This effort will likely improve the situation on PBP, too. What I've come up
with is a solution that will not require modifying any mainline drivers.
I wrote two new drivers that are needed for this to work. One for rk818
charger, that is needed to update the input current limit of the rk818 based on
whatever is negotiated by the Type-C port driver and USB 2.0 phy (according to
BC1.2 spec). The other driver is for bridging Type-C driver's native
interfaces to extcon bus.
I'm quite close to first boot tests of this new approach. So, there will
likely be some exciting news from me soon. ;)