Intel
®
81341 and 81342—Address Translation Unit (PCI Express)
Intel
®
81341 and 81342 I/O Processors
Developer’s Manual
December 2007
348
Order Number: 315037-002US
3.16.59 PCI Express Device Control Register - PE_DCTL
This register controls various modes and features of ATU and Message Unit when
operating in the PCI Express mode.
Table 193. PCI Express Device Control Register - PE_DCTL (Sheet 1 of 2)
Bit
Default
Description
15
0
2
Preserved
14:12
010
2
Max_Read_Request_Size – This field sets the maximum Read Request size for the Device as a
Requester. The Device must not generate read requests with size exceeding the set value.
Defined encodings for this field are:
000b 128B max read request size
001b 256B max read request size
010b 512B max read request size
011b 1024B max read request size
100b 2048B max read request size
101b 4096B max read request size
110b Reserved
111b Reserved
Any reserved value is treated as 4096B.
Note:
In a multifunction configuration, the minimum programmed value from all functions is used
when issuing requests.
11
1
Enable No Snoop
10
0
Aux Power PM Enable - The ATU does not utilize Auxiliary power. Hard-wired to 0.
9
0
Phantom Functions Enable - 81341 and 81342 does not use phantom functions. Hard-wired to 0.
8
0
Extended Tag Field Enable - 81341 and 81342 does not generate 8 bit tags. Hard-wired to 0.
7:5
000
Max_Payload_Size – This field sets maximum TLP payload size for the device. As a receiver, the device
must handle TLPs as large as the set value; as transmitter, the device must not generate TLPs exceeding
the set value.
Defined encodings for this field are:
000b 128B max payload size
001b 256B max payload size
010b 512B max payload size
011b 1024B max payload size (Unsupported)
100b 2048B max payload size (Unsupported)
101b 4096B max payload size (Unsupported)
110b Reserved
111b Reserved
Any unsupported or reserved value is treated as 128B.
Note:
In a multifunction configuration, the minimum programmed value from all functions is used
when transmitting packets, and checking for max_payload violations.
4
1
Enable Relaxed Ordering
3
0
Unsupported Request Reporting Enable – This bit in conjunction with other bits controls the signaling of
Unsupported Requests by sending Error Messages. For a multi-function device, this bit controls error
reporting from the point-of-view of the respective function.
PCI
IOP
Attributes
Attributes
15
12
8
4
0
pr
pr
rw
rw
rw
rw
rw
rw
rw
rw
ro
ro
ro
ro
ro
ro
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
Attribute Legend:
RV = Reserved
PR = Preserved
RS = Read/Set
RW = Read/Write
RC = Read Clear
RO = Read Only
NA = Not Accessible
Internal Bus Address Offset
+0D8H