See my response to tpmoney - not all signals in the DFU port go to the port controller.

> Doesn't that linked webarchive page say specifically that the ACE is a "Apple/TI co-designed USB Type-C Port Controller" If that isn't a "USB Controller" what do you mean when you say "USB Controller"? "USB controller" in common parlance means a USB host controller, the hardware that actually controls the USB signals and interfaces with the host CPU(s). They are required no matter if the physical port is type A, B, C, ... A "port controller" is something completely different, but still related to the "USB type C port" specification. It's a piece of logic (in this case in a separate IC) that handles things like negotiating PD, as well as which protocol(s) will be used over the high speed lanes etc. See the section about pin usage in different modes: https://en.wikipedia.org/wiki/USB-C comex's comment is inaccurate with respect to the commonly understood meaning of "USB controller" - while that port does have the CC lines going to ACE, the actual USB data lines go to the Apple SoC directly. This is contrasted with a different design where the USB data lines could go to a standalone IC, and that IC is connected to the Apple SoC via PCIe for example. DFU is significantly more complicated in this type of design because it requires bootstrapping and interaction with this external component.