[coreboot] usb3/xhci issues with coreboot on Thinkpad x230

[merino at aaathats3as.com]

Hello,

I noticed that OpenBSD 6.2 doesn't work well with the usb3 ports
on my Thinkpad x230. Filled a bug report on the openbsd-bugs ml[1].

After some more debugging, it seems that this is an OS independent
problem related to coreboot[2]. Flashing the Thinkpad with stock
BIOS made the usb3 ports work without issues.

I tested it with the coreboot build as seen in the dmesg output[1]
and with a coreboot directly built from git. The issue exists with
both builds. Build from git was done by:

$ git clone https://review.coreboot.org/coreboot
$ cd coreboot
$ git submodule update --init --checkout

Set the following options:
- Mainboard vendor (Lenovo)
- Mainboard model (ThinkPad X230)
- [*] PS/2 keyboard init
- (10) PS/2 keyboard controller initialization timeout (milliseconds)

Everything else was left on the default setting.

$ make crossgcc-x64 CPUS=4
$ make -j4

I still have one x230 equipped with coreboot to play with.
Please let me know what tests I should do with it to debug this.

-merino

[1] https://marc.info/?l=openbsd-bugs&m=151482559023666&w=2
[2] https://marc.info/?l=openbsd-bugs&m=151491851711586&w=2