Altera RapidIO MegaCore Function - Manual (Page 108)

4–62 Chapter 4: Functional Description
Error Detection and Management
RapidIO MegaCore Function August 2014 Altera Corporation
User Guide
The RapidIO IP core Physical layer transparently manages these errors for you. The
RapidIO specification defines both input and output error detection and recovery
state machines that include handshaking protocols in which the receiving end signals
that an error is detected by sending a packet-not-accepted control symbol, the
transmitter then sends an input-status link-request control symbol to which the
receiver responds with a link-response control symbol to indicate which packet
requires transmission. The input and output error detection and recovery state
machines can be monitored by software that you create to read the status of the Port
0 Error and Status
CSR ( Table 6–10 on page 6–7 ).
In addition to the registers defined by the specification, the RapidIO IP core provides
several output signals that enable user logic to monitor error detection and the
recovery process. Refer to
“Status Packet and Error Monitoring Signals” on page 5–2 .
Protocol Violations
Some protocol violations, such as a packet with an unexpected ackID or a time-out on
a packet acknowledgment, can use the same error recovery mechanisms as the
transmission errors described in
“Physical Layer Error Management” on page 4–61 .
Some protocol violations, such as a time-out on a link-request or the RapidIO IP core
receiving a link-response with an ackID outside the range of transmitted ackIDs, can
lead to unrecoverable—or fatal—errors.
Fatal Errors
Fatal errors cause a soft reset of the Physical layer module, which clears all the
transmit buffers and resets the transmission and expected ackID to zero. This effect
also can be triggered by software by first writing a one and then a zero to the PORT_DIS
bit of the Port 0 Control CSR (
Table 6–11 on page 6–10 ).
If the link partner is reset when its expected ackID is not zero, a fatal error occurs
when the link partner receives the next transmitted packet because the link partner’s
expected ackID is reset to zero, which causes a mismatch between the transmitted
ackID
and the expected ackID. The fatal error causes a soft reset of the IP core. After
the soft reset completes, transmitted and expected ackIDs are synchronized and
normal operation resumes. Only the packets that were queued at the time of the fatal
error are lost.
If Send link-request reset-device on fatal errors is turned on in the RapidIO
parameter editor, fatal errors cause the transmitter to send link-request control
symbols with cmd set to reset-device to the link partner.
Logical Layer Error Management
The Logical layer modules only need to process Logical layer errors because errors
detected by the Physical layer are masked from the Logical layer module. Any packet
with an error detected in the Physical layer is dropped in the Physical layer or the
Transport layer before it reaches the Logical layer modules.
The RapidIO specification defines the following common errors and the protocols for
managing them:
■ Malformed request or response packets
■ Unexpected Transaction ID