XIO2000AI TAOS [TEXAS ADVANCED OPTOELECTRONIC SOLUTIONS], XIO2000AI Datasheet - Page 82

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

Classic PCI Configuration Space
4.50 Device Control Register
k
72
This bit is sticky and must retain its value when the bridge is powered by V AUX .
14:12
10
BIT
7:5
15
11
9
8
4
k
SCPS155C
The device control register controls PCI Express device specific parameters. See Table 4−26 for a complete
description of the register contents.
CFG_RTRY_ENB
RESET STATE
BIT NUMBER
FIELD NAME
PCI register offset:
Register type:
Default value:
MRRS
APPE
ETFE
ENS
MPS
ERO
PFE
15
ACCESS
0
RW
RW
RW
RW
RW
R
R
R
14
Table 4−26. Device Control Register Description
0
Configuration retry status enable. When this read/write bit is set to 1b, the bridge returns a
completion with completion retry status on PCI Express if a configuration transaction forwarded
to the secondary interface did not complete within the implementation specific time-out period.
When this bit is set to 0b, the bridge does not generate completions with completion retry status
on behalf of configuration transactions. The default value of this bit is 0b.
Maximum read request size. This field is programmed by host software to set the maximum size
of a read request that the bridge can generate. The bridge uses this field in conjunction with the
cache line size register (offset 0Ch, see Section 4.6) to determine how much data to fetch on a
read request. This field is encoded as:
Enable no snoop. Controls the setting of the no snoop flag within the TLP header for upstream
memory transactions mapped to any traffic class mapped to a virtual channel (VC) other than
VC0 through the upstream decode windows.
Auxiliary power PM enable. This bit has no effect in the bridge.
Phantom function enable. Since the bridge does not support phantom functions, this bit is
read-only 0b.
Extended tag field enable. Since the bridge does not support extended tags, this bit is read-only
0b.
Maximum payload size. This field is programmed by host software to set the maximum size of
posted writes or read completions that the bridge can initiate. This field is encoded as:
Enable relaxed ordering. Since the bridge does not support relaxed ordering, this bit is read-only
0b.
13
1
000 = 128B
001 = 256B
010 = 512B (default)
011 = 1024B
100 = 2048B
101 = 4096B
110 = Reserved
111 = Reserved
0 = No snoop field is 0b
1 = No snoop field is 1b (default)
0 = AUX power is disabled (default)
1 = AUX power is enabled
000 = 128B (default)
001 = 256B
010 = 512B
011 = 1024B
100 = 2048B
101 = 4096B
110 = Reserved
111 = Reserved
98h
Read-only, Read/Write
2800h
12
0
11
1
10
0
9
0
8
0
DESCRIPTION
7
0
6
0
5
0
April 2007 Revised October 2008
4
0
3
0
2
0
1
0
0
0