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AR# 64062

UltraScale GTY RX reset in Near End PMA loopback (TX->RX serial loopback)

Description

Data integrity failure and rotating RXOUTCLK can occur occasionally after a GTRXRESET when in near end PMA loopback mode at line rates above 25 Gbps.

Solution

Use the following reset sequence when using near end PMA loopback for high line rates >= 25G

1. Have GTY in non loopback mode (LOOOPBACK=3'b000), reset using GTRXRESET.
 
2. Put GTY in near end PMA looopback (LOOPBACK=3'b010).
 
3. Reset RX using RXPMARESET.
 
If line rate is < 25G, the GTY can be put into near end PMA loopback reset normally without issue and the above sequence is not needed.
AR# 64062
Date Created 03/26/2015
Last Updated 04/17/2015
Status Active
Type General Article
Devices
  • Virtex UltraScale