Parameter
Value
Description
Port type
Native Endpoint
Root Port
Specifies the port type.
The Endpoint stores parameters in the Type 0
Configuration Space. The Root Port stores
parameters in the Type 1 Configuration Space.
Root Port is not supported for the Avalon-MM
with DMA interface.
RX Buffer
credit
allocation -
performance
for received
requests
Minimum
Low
Balanced
High
Maximum
Determines the allocation of posted header
credits, posted data credits, non-posted header
credits, completion header credits, and
completion data credits in the 16 KB RX buffer.
The settings allow you to adjust the credit
allocation to optimize your system.
The credit allocation for the selected setting
displays in the Message pane. The Message pane
dynamically updates the number of credits for
Posted, Non-Posted Headers and Data, and
Completion Headers and Data as you change
this selection.
Refer to the
Throughput Optimization
chapter
for more information about optimizing your
design.
Refer to the
RX Buffer Allocation Selections
Available by Interface Type
below for the
availability of these settings by interface type.
Minimum—configures the minimum PCIe
specification allowed for non-posted and posted
request credits, leaving most of the RX Buffer
space for received completion header and data.
Select this option for variations where applica‐
tion logic generates many read requests and only
infrequently receives single requests from the
PCIe link.
Low—configures a slightly larger amount of RX
Buffer space for non-posted and posted request
credits, but still dedicates most of the space for
received completion header and data. Select this
option for variations where application logic
generates many read requests and infrequently
receives small bursts of requests from the PCIe
link. This option is recommended for typical
endpoint applications where most of the PCIe
4-2
System Settings
UG-01145_avmm_dma
2015.11.02
Altera Corporation
Parameter Settings
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