IDT sRIO Ports
Revision 1.5
Integrated Device Technology, Inc.
CPS-16/12/8 User Manual
2 - 8
July 10, 2012
2.4.2 Link Maintenance CSR Reset Command field
A write to the Port n Maintenance CSR with the command field set to 0b011 (reset) the device will:
1) cease all current and pending transmissions (data and SRIO control symbols -- including multi-
cast control symbols),
2) transmit 4 link request -- reset symbols in succession. After transmitting the link request -- reset
symbols, the port will enter the output error state and wait for a corresponding link response.
2.4.3 Usage Definition for Port n Link Maintenance Response CSRs
The Port n Link Maintenance Response CSRs will be read only registers which contain the information
contained in the most recently received link response by the specific port. When read, it will return the data.
2.4.4 Usage Definition for Port n Local ACK ID CSRs
The CLR_OUTSTANDING_ACKIDs, INBOUND_ACKID, OUTSTANDING_ACKID, & OUTBOUND_ACKID
fields defined for this register are supported.
2.4.4.1 CLR_OUTSTANDING_ACKIDs
This single bit field will be treated as write only. When this bit is written to a value of 1, CPS treats all previ-
ously transmitted packet for which acks have not been received as having been properly received by the
link partner. Acknowledgment processing for these packets will no longer be required.
2.4.4.2 INBOUND_ACKID
CPS supports both reads from and writes to the INBOUND_ACKID parameter. If read, CPS will return the
value of the expected ack ID of the next received packet.
A write of this parameter will set the expected ack ID for the next received packet to the value supplied with
the write. If the port receiver state machine is in a stopped state it will return to the normal operational state
after updating the expected ID value. If a packet is being received during this transition, it will be dropped
without response.
2.4.4.3 OUTBOUND ACKID
CPS supports both reads from and writes to the OUTBOUND_ACKID parameter. If read, CPS will refer to
the value that the device will use for the next transmitted packet ack.
If written, the effect will be dependant upon whether or not there are outstanding ackIDs. If there are no
outstanding ackIDs, the next transmitted packet will use the ackID written into this register. If there are
outstanding ack IDs, the packets that have been previously transmitted (without the device having received
an acknowledgement), will be retransmitted using ack IDs which start from the value written into this
register.
2.4.4.4 OUTSTANDING ACKID
CPS supports both reads from and writes to the OUTSTANDING_ACKID parameter. If read, this parameter
will indicate the value of the next expected acknowledgement (control symbol ack ID field) from the port’s
link partner. The effect of writing this parameter will depend upon the current state of the port’s outstanding
ack ID status as follows:
1) If the port has no outstanding ack IDs the write will have no effect on the port. Because of the
Outstanding AckID always reflects the ackID that the port expects to received next, so if the out-
bound ID change, then the outstanding ID will be changed.
2) If the port has outstanding ack IDs and the written value is one of them, the port will accept all
existing ack IDs with lower values. Which means the port will accept the existing packets with this
written value ackID and following values. The write in this case will have no effect on the ack ID of
the next packet to be transmitted.
3) If the port has outstanding ack IDs and the written value is not one of them an error will be
recorded and the port will take no action.