Intel 41210 User Manual
Intel
®
41210 Serial to Parallel PCI Bridge Developer’s Manual
93
Register Description
12.2.28
Offset 4Ch: EXP_DCTL—PCI Express* Device Control
Register
Register
This register stores command bits that control the 41210 behavior on PCI Express*.
Table 62.
Offset 4Ch: EXP_DCTL—PCI Express* Device Control Register (Sheet 1 of 2)
Bits
Type
Default
Description
15
RW
0b
Bridge Configuration Retry Enable:
When set, the bridge is enabled to return a
completion with Completion Retry Status (CRS) on PCI Express* when a configuration
transaction to the secondary interface did not complete within the PCI completion time-out
period.
transaction to the secondary interface did not complete within the PCI completion time-out
period.
14:12
RW
010b
Max_Read_Request_Size:
This field applies to the bridge segment when the segment is in
PCI mode only. When in PCI-X mode, this field does not apply. The Intel
®
41210 Serial to
Parallel PCI Bridge cannot send requests larger than the size indicated by this field.
Encodings are as follows:
Encodings are as follows:
11
RO
0b
Enable No Snoop:
Hard-wired to 0
10
RO
0b
Auxiliary (AUX) Power PM Enable:
Not supported
9
RO
0b
Phantom Function Enable:
Not supported
8
RO
0b
Extended Tag Field Enable:
Ignored because only 5-bit tag is supported
7:5
RW
000b
Maximum Payload Size:
These bits indicate the maximum payload size supported for
TLPs. Supported encodings are as follows:
All other values default to 128 bytes.
4
RO
0b
Enable Relaxed Ordering:
Hard-wired to 0
3
RW
0b
Unsupported Request Reporting Enable:
This bit controls the enabling of
ERR_NONFATAL or ERR_FATAL messages on PCI Express* for reporting “Unsupported
Request” errors. Note that the following requests use this enable bit:
Request” errors. Note that the following requests use this enable bit:
•
requests from PCI Express* that are unsupported
•
requests from PCI Express* that master-abort on the internal switch
Bit
Max_Read_Request_Size
000b
128-byte maximum read request size
001b
256-byte maximum read request size
010b
512-byte maximum read request size
011b
1024-byte maximum read request size
100b
2048-byte maximum read request size
101b
4096-byte maximum read request size
110b
Reserved (the 41210 defaults to 512 bytes)
111b
Reserved (the 41210 defaults to 512 bytes)
Bit
Max_Payload_Size
000b
128-byte maximum payload size
001b
256-byte maximum payload size