The latency information includes the latencies that are associated with upstream links and controller.įor the DS port to which the device is attached, the software configures two values: PORT_U1_TIMEOUT and PORT_U2_TIMEOUT. As the second part of the exchange, the host informs the device about overall exit latencies for the device by sending a SET_SEL control transfer, as per section 9.4.12 of the USB 3.0 specification. As the first part of this exchange, the device-specific latencies are filled in by the device in bU1DevExitLat and wU2DevExitLat fields of the SuperSpeed USB device capability (defined in Section 9.6.2.2 of the USB 3.0 specification). Software exchanges U1 or U2 exit latency information with the device during the enumeration process. This topic describes how software enumerates a device.įor U1 or U2 transitions to occur, software performs the following steps during the enumeration of a device. This topic first describes the initial setup that is done by the software to enable U1 and U2 transitions, and then describes how these transitions occur in the hardware.
0 Comments
Leave a Reply. |