The DataMover S2MM function can be parameterized to enable support for stream data transfer of an indeterminate number of bytes. This is defined as where the S2MM is commanded (by the BTT command field) to transfer a fixed number of bytes, but it is unknown how many bytes are actually going to be received from the incoming stream interface (at the assertion of
s_axis_s2mm_tlast
). Supporting this operation mode requires additional hardware in the S2MM function, and additional fields in the status word indicating the actual count of the bytes received from the stream interface for the commanded transfer, and whether the
tlast
was received during the transfer.
The format of the S2MM status word with Indeterminate BTT mode enabled is shown in
This Figure
and detailed in
Table: Special S2MM Status Word Details (Indeterminate BTT Mode Enabled)
. This status format does not apply to the MM2S DataMover status interface. See
Indeterminate BTT Mode
for more information.
Figure 2-4:
S2MM Status Format in IBTT Mode
|
X-Ref Target - Figure 2-4
|
Table 2-9:
Special S2MM Status Word Details (Indeterminate BTT Mode Enabled)
|
Bits
|
Field Name
|
Description
|
|
31
|
EOP
|
End of Packet
This bit indicates that the S2MM Stream input received a tlast assertion during the execution of the DataMover command associated with the status word. This is not an error condition.
|
|
30 to 8
|
BRCVD
|
Bytes Received
This field indicates the actual number of bytes received on the stream interface at the point where s_axis_s2mm_tlast was asserted by the Stream Master.
|
|
7
|
OKAY
|
Transfer OKAY
This bit indicates that the associated transfer command has been completed with the OKAY response on all intermediate transfers.
0 = Command had a non-OKAY response during all associated transfers.
1 = Command had a OKAY response during all associated transfers.
|
|
6
|
SLVERR
|
Slave Error
Indicates the DataMover encountered a slave reported error condition for the associated command. This is received by the response inputs from the AXI4 interface.
0 = No Error
1 = Slave Asserted Error Condition
|
|
5
|
DECERR
|
Decode Error
Indicates the DataMover encountered an address decode error condition for the associated command. This is received by the response inputs from the AXI4 interface and indicates an address decode timeout occurred on an address generated by the DataMover element while executing the corresponding command.
0 = No Error
1 = Address Decode Error Condition
|
|
4
|
INTERR
|
Internal Error
Indicates the DataMover encountered an internal error condition for the associated command. A BTT (Bytes to Transfer) value of 0 (zero) in the command word can cause this assertion.
Additional conditions are to be determined.
0 = No Error
1 = Internal Error Condition
|
|
3 to 0
|
TAG
|
TAG
This 4-bit field echoes the value of the TAG field of the associated input command whose completion generated the status.
|
