XIO2000AI TAOS [TEXAS ADVANCED OPTOELECTRONIC SOLUTIONS], XIO2000AI Datasheet - Page 120

• Manufacturer Part Number: XIO2000AI
• Description: PCI Express to PCI Bus Translation Bridge
• Manufacturer: TAOS [TEXAS ADVANCED OPTOELECTRONIC SOLUTIONS]

PCI Express Extended Configuration Space
5.18 Port VC Capability Register 2
110
31:24
23:8
BIT
7:0
SCPS155C
The second port VC capability register provides information to software regarding the VC arbitration schemes
supported by the bridge. See Table 5−14 for a complete description of the register contents.
RESET STATE
RESET STATE
VC_ARB_CAP
TBL_OFFSET
BIT NUMBER
BIT NUMBER
FIELD NAME
VC_ARB_
PCI Express extended register offset:
Register type:
Default value:
RSVD
ACCESS
31
15
0
0
RU
RU
R
Table 5−14. Port VC Capability Register 2 Description
30
14
0
0
VC arbitration table offset. If bits 6:4 (LOW_PROIRITY_COUNT) in the port VC capability register 1
(offset 154h, see Section 5.17) are 000b, then this field returns 00h when read. Otherwise, this
read-only field returns the value 03h to indicate that the VC arbitration table begins 48 bytes from
the top of the VC capability structure. When this field equals 00h, the VC arbitration table is a
scratch pad and has no effect in the bridge.
Reserved. Returns 0000h when read.
VC arbitration capability. This 8-bit encoded field indicates support for the various schemes that are
supported for VC arbitration. The field is encoded as follows:
Bit 0 = Hardware fixed arbitration (round-robin)
Bit 1 = WRR with 32 phases
Bit 2 = WRR with 64 phases
Bit 3 = WRR with 128 phases
Bit 4 = Reserved
Bit 5 = Reserved
Bit 6 = Reserved
Bit 7 = Reserved
If bits 6:4 (LOW_PROIRITY_COUNT) in the port VC capability register 1 (offset 154h, see
Section 5.17) are 000b, then this field returns 00h when read. Otherwise, this field returns 03h to
indicate that hardware-fixed round-robin and WRR with 32 phases are both supported.
29
13
0
0
28
12
0
0
27
11
0
0
26
10
0
0
158h
Read-only
0X00 000Xh
25
x
9
0
24
8
0
x
DESCRIPTION
23
0
7
0
22
0
6
0
21
0
5
0
April 2007 Revised October 2008
20
0
4
0
19
0
3
0
18
0
2
0
17
0
1
x
16
0
0
x