Datasheet

xHCI Controller Registers (D20:F0)
Intel® Xeon® Processor D-1500 Product Family 463
Datasheet - Volume 1 of 4: Integrated Platform Controller Hub
March 2015
Bit Description
31:16 dB Stream ID — R/W. If the endpoint of a Device Context Doorbell defines Streams, then this field
shall be used to identify which Stream of the endpoint the doorbell reference is targeting. System
software is responsible for ensuring that the value written to this field is valid.
If the endpoint does not define Streams (MaxPStreams = 0) and a non-'0' value is written to this
field, the doorbell reference shall be ignored.
This field only applies to Device Context Doorbells and shall be cleared to ‘0’ for Host Controller
Commands.
This field returns ‘0’ when read.
15:8 Reserved.
7:0 dB Target — R/W. This field defines the target of the doorbell reference. The table below defines the
xHC notification that is generated by ringing the doorbell. The Doorbell Register 0 is dedicated to
Command Ring and decodes this field differently than the other Doorbell Registers.
Refer to the xHCI Specification for definitions of the values.