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Protocols — USB Support
Version 1.10 12/01/02 14-65
14.2.6.2 USB Device Path Example
Table 14-4 shows an example device path for a USB controller on a desktop platform. This USB
Controller is connected to the port 0 of the root hub, and its interface number is 0. The USB Host
Controller is a PCI device whose PCI device number 0x1F and PCI function 0x02. So, the whole
device path for this USB Controller consists an ACPI Device Path Node, a PCI Device Path Node,
a USB Device Path Node and a Device Path End Structure. The _HID and _UID must match the
ACPI table description of the PCI Root Bridge. The shorthand notation for this device path is:
ACPI(PNP0A03,0)/PCI(1F|2)/USB(0,0).
Table 14-4. USB Device Path Examples
Byte
Offset
Byte
Length
Data
Description
0x00 0x01 0x02 Generic Device Path Header – Type ACPI Device Path
0x01 0x01 0x01 Sub type – ACPI Device Path
0x02 0x02 0x0C Length – 0x0C bytes
0x04 0x04 0x41D0,
0x0A03
_HID PNP0A03 – 0x41D0 represents a compressed string ‘PNP’ and is in
the low order bytes
0x08 0x04 0x0000 _UID
0x0C 0x01 0x01 Generic Device Path Header – Type Hardware Device Path
0x0D 0x01 0x01 Sub type – PCI
0x0E 0x02 0x06 Length – 0x06 bytes
0x10 0x01 0x1F PCI Function
0x11 0x01 0x02 PCI Device
0x12 0x01 0x03 Generic Device Path Header – Type Message Device Path
0x13 0x01 0x05 Sub type – USB
0x14 0x02 0x06 Length – 0x06 bytes
0x16 0x01 0x00 Parent Hub Port Number.
0x17 0x01 0x00 Controller Interface Number.
0x18 0x01 0xFF Generic Device Path Header – Type End of Hardware Device Path
0x19 0x01 0xFF Sub type – End of Entire Device Path
0x1A 0x02 0x04 Length – 0x04 bytes