X200 dock has been broken since November 2019

[Kevin Keijzer]

I have a couple of X200's, all running coreboot 4.10. The dock works 
fine there. When I press the undock button (either on the side or with 
Fn+F9), the system undocks, and when I put the laptop back in the dock, 
the led goes red again, and the USB ports start working again. The same 
happens when the system is suspended and resumed.

However, since coreboot 4.11, the re-docking part is completely broken. 
I can press the undock button(s), which work fine, but when I re-dock 
the laptop, the led remains green and USB does not work. Also, when I 
suspend and resume the laptop, the system undocks immediately after 
resuming from S3, even though no button was pressed and it's still 
physically docked.

The only way to recover from this is by rebooting.

In coreboot 4.13, this bug is still present. So I decided to bisect the 
issue, and I found the offending commit:

96ae7a3a2d38b96c1dfee57fda2c2eaab7e9e762 is the first bad commit
commit 96ae7a3a2d38b96c1dfee57fda2c2eaab7e9e762
Author: Bill XIE 
Date:   Wed Oct 16 23:22:10 2019 +0800

mb/lenovo/x200: Add ThinkPad X301 as a variant

It is similar to X200s, with U-series CPU, slightly different gpio
     setup, no docking support, and no superio chip.

https://review.coreboot.org/c/coreboot/+/36093

Looking at the changes, this seems pretty plausible. I would like to get 
coreboot 4.14 running properly again with docked X200's, but I'm not 
sure (yet) what the exact cause of the breakage is.

[Nico Huber]

Hi Kevin,

On 28.02.21 14:36, Kevin Keijzer via coreboot wrote:
> In coreboot 4.13, this bug is still present. So I decided to bisect the
> issue, and I found the offending commit:
>
> 96ae7a3a2d38b96c1dfee57fda2c2eaab7e9e762 is the first bad commit

thanks for the bisecting effort! I think I found the problematic line,
can you please test
  https://review.coreboot.org/c/coreboot/+/51118

Nico

[Kevin Keijzer]

Hi Nico,

This change indeed fixes the redocking part. However, resuming from S3 
still causes the system to be undocked, which was not the case in 
coreboot 4.10 (and is probably not desired behaviour).

I can now physically undock and redock the X200 after resume from S3 to 
get USB back to work though, which is a lot better than having to reboot.

Also, the undock button on the side of the dock still doesn't work with 
this change, but Fn+F9 does.

So it's definitely an improvement, but not a complete fix.