82801FB Datasheet, PDF (546/786 Pages) Intel Corporation – Intel I/O Controller Hub 6 (ICH6) Family

EHCI Controller Registers (D29:F7)
14.2.1.4
HCCPARAMS—Host Controller Capability Parameters
Register
Offset:
Default Value:
MEM_BASE + 08–0Bh
00006871h
Attribute: RO
Size:
32 bits
Bit
Description
31:16
15:8
7:4
3
2
1
0
Reserved
EHCI Extended Capabilities Pointer (EECP) — RO. This field is hardwired to 68h, indicating that the
EHCI capabilities list exists and begins at offset 68h in the PCI configuration space.
Isochronous Scheduling Threshold — RO. This field indicates, relative to the current position of the
executing host controller, where software can reliably update the isochronous schedule. When bit 7
is 0, the value of the least significant 3 bits indicates the number of micro-frames a host controller
hold a set of isochronous data structures (one or more) before flushing the state. When bit 7 is a 1,
then host software assumes the host controller may cache an isochronous data structure for an
entire frame. Refer to the EHCI specification for details on how software uses this information for
scheduling isochronous transfers.
This field is hardwired to 7h.
Reserved. These bits are reserved and should be set to 0.
Asynchronous Schedule Park Capability — RO. This bit is hardwired to 0 indicating that the host
controller does not support this optional feature
Programmable Frame List Flag — RO.
0 = System software must use a frame list length of 1024 elements with this host controller. The
USB2.0_CMD register (D29:F7:CAPLENGTH + 20h, bits 3:2) Frame List Size field is a read-
only register and must be set to 0.
1 = System software can specify and use a smaller frame list and configure the host controller via
the USB2.0_CMD register Frame List Size field. The frame list must always be aligned on a 4K
page boundary. This requirement ensures that the frame list is always physically contiguous.
64-bit Addressing Capability — RO. This field documents the addressing range capability of this
implementation. The value of this field determines whether software should use the 32-bit or 64-bit
data structures. Values for this field have the following interpretation:
0 = Data structures using 32-bit address memory pointers
1 = Data structures using 64-bit address memory pointers
This bit is hardwired to 1.
NOTE: ICH6 only implements 44 bits of addressing. Bits 63:44 will always be 0.
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Intel^® I/O Controller Hub 6 (ICH6) Family Datasheet