Altera Cyclone V - Device

3–4 Chapter 3: Parameter Settings
Port Functions
Cyclone V Hard IP for PCI Express November 2011 Altera Corporation
Device
Table 3–2 describes the shared device parameters.
Table 3–2. Capabilities Registers for Function <n> (Part 1 of 2)
Parameter
Possibl
e
Values
Default
Value
Description
Device Capabilities
Maximum
payload size
0x084
128
bytes
256
bytes,
512
bytes,
128 bytes
Specifies the maximum payload size supported. This
parameter sets the read-only value of the max payload size
supported field of the Device Capabilities register (0x084[2:0])
and optimizes the IP core for this size payload.
Number of tags
supported
supported per
function
32
64
32
Indicates the number of tags supported for non-posted
requests transmitted by the Application Layer. This parameter
sets the values in the Device Control register (0x088) of the
PCI Express Capability Structure described in Table 6–8 on
page 6–4.
The Transaction Layer tracks all outstanding completions for
non-posted requests made by the Application Layer. This
parameter configures the Transaction Layer for the maximum
number to track. The Application Layer must set the tag values
in all non-posted PCI Express headers to be less than this
value. Values greater than 32 also set the extended tag field
supported bit in the C
onfiguration Space Device
Capabilities
register. The Application Layer can only use
tag numbers greater than 31 if configuration software sets the
Extended Tag Field Enable bit of the Device Control
register. This bit is available to the Application Layer as
cfg_devcsr[8] .
Completion
timeout range
ABCD
BCD
ABC
AB
B
A
None
ABCD
Indicates device function support for the optional completion
timeout programmability mechanism. This mechanism allows
system software to modify the completion timeout value. This
field is applicable only to Root Ports and Endpoints that issue
requests on their own behalf. Completion timeouts are
specified and enabled in the Device Control 2 register (0x0A8)
of the PCI Express Capability Structure Version 2.0 described
in Table 6–8 on page 6–4. For all other functions this field is
reserved and must be hardwired to 0x0000b. Four time value
ranges are defined:
■ Range A: 50 µs to 10 ms
■ Range B: 10 ms to 250 ms
■ Range C: 250 ms to 4 s
■ Range D: 4 s to 64 s
Bits are set to show timeout value ranges supported. 0x0000b
completion timeout programming is not supported and the
function must implement a timeout value in the range 50 s to
50 ms.