[coreboot] Why is subsystemid required to find a uPD7020200

[Nico Huber]

On 15.11.2016 03:03, Charlotte Plusplus wrote:
> Hello
> 
> The USB3 on a W520 is provided by a uPD7020200 on PCIe port 7, so I just
> had in my device tree:
>     device pci 1c.6 on end
> 
> Yet in the boot I was getting:
>      PCI: Static device PCI: 00:1c.6 not found, disabling it.

This error message is unrelated to the subsystem id. In this case, core-
boot can't even set the id. It looks more like 00:1c.6 was (still?) dis-
abled through the function disable (FD) register? I don't know if it
gets cleared on every reboot.Do you still set it in early romstage?

Nico

> 
> After googlging about this, I found the x230 uses subsystemid
>      device pci 1c.6 on subsystemid 0x17aa 0x21db end
> 
> After trying that, I could get the USB3 to be detected and working
> correctly on the W520.
> 
> Nowhere else I need subsystemid, so I don't understand why it is needed
> here.
> I don't want to copy something I don't understand, especially if it may be
> needed in other places.
> 
> Could someone explain when subsystemid is required?
> 
> Thanks
> Charlotte
> 
> 
>