Re: Question about connecting USB HID devices.

["Zeng, Star" <star.zeng@intel.com>]

It is about USB short form device path handling? Check https://github.com/tianocore/edk2/blob/master/MdeModulePkg/Bus/Usb/UsbBusDxe/UsbUtility.c#L1368?

Thanks,
Star
-----Original Message-----
From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of Andrew Fish
Sent: Friday, May 4, 2018 6:28 AM
To: edk2-devel <edk2-devel@lists.01.org>
Subject: [edk2] Question about connecting USB HID devices.

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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