[edk2] Question about connecting USB HID devices.

[Andrew Fish]

I was looking at this code: 
https://github.com/tianocore/edk2/blob/master/IntelFrameworkModulePkg/Library/GenericBdsLib/BdsConnect.c#L405
 
<https://github.com/tianocore/edk2/blob/master/IntelFrameworkModulePkg/Library/GenericBdsLib/BdsConnect.c#L405>

        Status = PciIo->Pci.Read (PciIo, EfiPciIoWidthUint8, 0x09, 3, &Class);
        if (!EFI_ERROR (Status)) {
          if ((PCI_CLASS_SERIAL == Class[2]) &&
              (PCI_CLASS_SERIAL_USB == Class[1])) {
            if (HostControllerPI == Class[0] || HostControllerPI == 0xFF) {
              Status = gBS->ConnectController (
                              HandleArray[Index],
                              NULL,
                              RemainingDevicePath,
                              FALSE
                              );
              if (!EFI_ERROR(Status)) {
                AtLeastOneConnected = TRUE;
              }
            }
          }
        }


I'm missing something? This code is doing a non-recursive ConnectController() 
on the PCI Handle for the USB HC. I would expect that this call would cause the 
creation of all the USB IO handles, or at least the ones that match 
RemainingDevicePath. In this code RemainingDevicePath is a USB Class device 
path node for HID devices. The main thing I don't understand is why the 
keyboard got connected?  I would think after this loop the BDS would need to 
loop on the created USB IO Protocols, call UsbGetInterfaceDescriptor() and do a 
recursive connect controller on the matching InterfaceClass. It looks like the 
USB bus driver may be connecting the console devices? I'm unclear why that work 
was not done in the BDS? 

Thanks,

Andrew Fish
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