USB_TRANSPORT_CHARACTERISTICS - NtDoc

Native API online documentation, based on the System Informer (formerly Process Hacker) phnt headers 
// usbioctl.h

typedef struct _USB_TRANSPORT_CHARACTERISTICS {
  ULONG   Version;
  ULONG   TransportCharacteristicsFlags;
  ULONG64 CurrentRoundtripLatencyInMilliSeconds;
  ULONG64 MaxPotentialBandwidth;
} USB_TRANSPORT_CHARACTERISTICS, *PUSB_TRANSPORT_CHARACTERISTICS;
View the official Windows Driver Kit DDI reference

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Windows Driver Kit DDI reference (ns-usbioctl-_usb_transport_characteristics)

_USB_TRANSPORT_CHARACTERISTICS structure

Description

Stores the transport characteristics at relevant points in time. This structure is used in the IOCTL_USB_GET_TRANSPORT_CHARACTERISTICS request.

Members

Version

The version is set to USB_TRANSPORT_CHARACTERISTICS_VERSION_1.

TransportCharacteristicsFlags

A bitmask that indicates to the client driver the transport characteristics that are available and are returned in this structure.

If USB_TRANSPORT_CHARACTERISTICS_LATENCY_AVAILABLE

is set, CurrentRoundtripLatencyInMilliSeconds contains valid information. Otherwise , it must not be used by the client driver.

If USB_TRANSPORT_CHARACTERISTICS_BANDWIDTH_AVAILABLE

is set, MaxPotentialBandwidth contains valid information. Otherwise, it must not be used by the client driver.

CurrentRoundtripLatencyInMilliSeconds

Contains the current round-trip delay in milliseconds from the time a non-isochronous transfer is received by the USB driver stack to the time that the transfer is completed.

For MA-USB, the underlying network could be WiFi, WiGig, Ethernet etc. The delay can vary depending on the underlying network conditions. A client driver should query the latency periodically or whenever it is notified of a change.

MaxPotentialBandwidth

Contains the total bandwidth of the host controller’s shared transport.

For MA-USB, the underlying network transport could be WiFi, WiGig, Ethernet etc. The total available bandwidth can vary depending on several factors such as the negotiation WiFi channel. A client driver should query the total bandwidth periodically or whenever it is notified of a change.

See also

IOCTL_USB_GET_TRANSPORT_CHARACTERISTICS

View the official Windows Driver Kit DDI reference

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