7–18
Chapter 7: Register Descriptions
PCI Express Avalon-MM Bridge Control Register Access Content
Arria V GZ Hard IP for PCI Express
November 2012
Altera Corporation
illustrates four dword TLPs with data that is aligned and unaligned to the
qword.
The TX TLP programming model scales with the data width. The Application Layer
performs the same writes for both the 64- and 128-bit interfaces. The Application
Layer can only have one outstanding non-posted request at a time. The Application
Layer must use tags 16–31 to identify non-posted requests.
Figure 7–1. Layout of Data with 3 DWord Headers
Figure 7–2. Layout of Data with 4 DWord Headers
Header 1 [63:32]
Cycle 1
Register 1
Register 0
Register 1
Register 0
Register 1
Register 0
Register 1
Register 0
Register 1
Register 0
Da
t
a Unaligned
t
o
Q
Wo
r
d Bounda
r
y
Da
t
a Aligned
t
o
Q
Wo
r
d Bounda
r
y
Cycle 2
Header 0 [31:0]
Data [63:32]
Header 2 [31:0]
Header 1 [63:32]
Cycle 1
Header 0 [31:0]
Cycle 2
Header 2 [31:0]
Unused, but must
be written
Cycle 3
Data [31:0]
Unused, but must
be written
Header 1 [63:32]
Cycle 1
Da
t
a Unaligned
t
o
Q
Wo
r
d Bounda
r
y
Da
t
a Aligned
t
o
Q
Wo
r
d Bounda
r
y
Cycle 2
Header 0 [31:0]
Header 3[63:32]
Header 2 [31:0]
Data [63:32]
Header 1 [63:32]
Header 0 [31:0]
Header 2 [31:0]
Cycle 1
Cycle 2
Cycle 3
Cycle 3
Data [31:0]
Unused, but must
be written
Unused, but must
be written
Header 3[63:32]
Register 1
Register 0
Register 1
Register 0
Register 1
Register 0
Register 1
Register 0
Register 1
Register 0
Register 1
Register 0