Intel® 400 Series Chipset On-Package Platform Controller Hub
Online Register Database
ID | Date | Version | Classification |
---|---|---|---|
615146 | 08/09/2019 | 1.2 | Public |
Structural Parameters 2 (HCSPARAMS2) – Offset 8
This register is modified and maintained by BIOS
Bit Range | Default | Access | Field Name and Description |
---|---|---|---|
31:27 | 02h | RW/L | Max Scratchpad Buffers LO (MaxScratchpadBufs) Indicates the number of Scratchpad Buffers system software shall reserve for the xHC. |
26 | 1b | RW/L | Scratchpad Restore (SPR) 0 = Indicates the Scratchpad buffer space may be freed and reallocated between power events. |
25:21 | 01h | RW/L | Max Scratchpad Buffers HI (MaxScratchpadBufs_HI)
|
20:8 | - | - | Reserved
|
7:4 | 5h | RW/L | Event Ring Segment Table Max (ERSTMax) This field determines the maximum value supported by the Event Ring Segment Table Base Size registers. |
3:0 | 4h | RW/L | Isochronous Scheduling Threshold (IST) This field indicates to system software the minimum distance (in time) that it is required to stay ahead of the xHC while adding TRBs, in order to have the xHC process them at the correct time. The value is specified in the number if frames/ microframes. If bit [3] of IST is cleared to 0b, software can add a TRB no later than IST [2:0] microframes before that TRB is scheduled to be executed. If bit [3] of IST is set to 1b, software can add a TRB no later than IST[2:0] frames before that TRB is scheduled to be executed. |