Altera Arria V GZ Avalon-ST User Manual
Page 266
Possible Causes
Symptoms and Root Causes
Workarounds and Solutions
Link fails due to
unstable
rx_
signaldetect
Confirm that
rx_signaldetect
bus of the active lanes is all 1’s.
If all active lanes are driving all
1’s, the LTSSM state machine
toggles between Detect.Quiet(0),
Detect.Active(1), and
Polling.Active(2) states.
This issue may be caused by mismatches
between the expected power supply to RX side
of the receiver and the actual voltage supplied to
the FPGA from your boards. If your PCB drives
VCCT/VCCR with 1.0 V, you must apply the
following command to both P and N pins of
each active channel to override the default
setting of 0.85 V.
set_instance_assignment -name XCVR_
VCCR_VCCT_VOLTAGE 1_0V –to “pin”
Substitute the pin names from your design for
“pin”
.
Link fails because the
LTSSM state machine
enters Compliance
Confirm that the LTSSM state
machine is in
Polling.Compliance(3) using
SignalTap II.
Possible causes include the following:
• Setting
test_in[6]
=1 forces entry to
Compliance mode when a timeout is reached
in the Polling.Active state.
• Differential pairs are incorrectly connected
to the pins of the device. For example, the
Endpoint’s TX signals are connected to the
RX pins and the Endpoint’s RX signals are to
the TX pins.
Debugging Link Failure in L0 Due To Deassertion of tx_st_ready
There are many reasons that link may stop transmitting data. The following table lists some possible
causes.
18-4
Debugging Link Failure in L0 Due To Deassertion of tx_st_ready
UG-01127_avst
2014.12.15
Altera Corporation
Debugging