USB 3.0 embedded hubs with their upstream ports connected to arbitrary root hub ports.

ACPI is required for describing more complex port mapping such as:

In the absence of ACPI, that mapping should be followed by hardware and assumed by software. The Busport-0048 requirement describes an intuitive default mapping that allows internal hubs. In certain scenarios, there might be a need to design add-in cards with hubs to allow for more external ports or as a way to support USB Low, Full and High Speed. If your add-in host controller does not contain an internal hub (integrated or embedded, defined in the xHCI specification), then you should follow the xHCI specification to map the ports. Design Considerations for Add-in Host Controllers The example does not provide details about how that mapping should be reported by add-in controllers, which is the focus of our post. The xHCI specification outlines an example of an embedded controller that uses ACPI information to communicate the port mapping. For systems with embedded controllers, there is a similar WLK requirement (Sysfund-226) however, the method for obtaining the information is different because integrated controllers use Advanced Configuration and Power Interface (ACPI) to define port mapping. Based on the information, the USB driver stack manages the ports appropriately. The goal of the Busport-0048 requirement is for add-in host controllers to provide information to the USB driver stack about the ports available on the controller in a consistent way.

In this blog post, we will describe a case study that includes two theoretical examples of the add-in controller designs (one approved and the other with the disallowed configuration). An add-in host controller is a card that is not integrated onto the motherboard. The requirement targets manufacturers of USB xHCI add-in host controllers. The Busport-0048 requirement states “ xHCI add-in cards must map USB 3.0 and USB 2.0 ports consistently”. My name is Jane Lawrence, and in this blog post, Philip Ries and I will describe the details of the Busport-0048 Windows Logo Kit (WLK) requirement that has been in effect since Dec 1, 2010.

Usb root hub xhci failed to reset