USB 3.0 support on Series 3 Docking Stations

[dr_st]

In a few past threads there were some attempts to reach a complete understanding of how the Series 3 Docks with USB 3.0 interact with various Thinkpads. Specifically - does the USB 3.0 port function as USB 3.0 or only USB 2.0?

See for example:
T520 & USB 3.0
Need some advice about USB 3.0 on w520 dock 4338
Thinkpad X220 and USB3 on Series 3 Docks *PIC Warning*

The docks do not include a USB 3.0 controller, and the port is merely pass-through, therefore systems that themselves do not include a USB 3.0 controller will have the port functioning as USB 2.0 only. This includes all first-generation Core (Ibex Peak chipset) and most second-generation Core (Sandy Bridge / Cougar Point) systems: *10 series, most *20 series, as well as the Core 2 T400s.

Systems that have USB 3.0 support built into the chipset (Ivy Bridge / Panther Point) have the port functioning as USB 3.0. This includes the *30 series.

With regards to Sandy Bridge / Cougar Point systems that have a third-party USB 3.0 controller by NEC/Renesas (the 2-port uPD720200), the results are mixed:

T420s - USB 2.0 (one USB 3.0 port routed to chassis, second USB 3.0 port not routed)
W520 - USB 2.0 (both USB 3.0 ports routed to chassis)
X220 i7 - USB 3.0 (one USB 3.0 port routed to chassis, one USB 3.0 port routed to dock).

This has been verified experimentally as well as by looking at schematics for said notebooks. According to the dates, the X220 schematics have been finalized much later than those for the T420s, probably when the USB 3.0 docks were already in planning / production, which can explain why it is the only system where special support for USB 3.0 docks was added.

To summarize the list of systems:

USB 3.0 port on dock functions as USB 2.0: T400s, T410, T410s, T420, T420s, T510, W510, T520, W520, L412, L512, L420, L520, X220 i3/i5
USB 3.0 port on dock functions as USB 3.0: T430, T430s, T431s, T530, W530, L430, L530, X220 i7, X230

Sources:
T420s (Wistron Shinai-3) Schematics
W520 (Wistron Kendo-3 WS) Schematics
X220 (Wistron Dasher-1) Schematics
X230 (Wistron Dasher-2) Schematics