Clause 48: Sync StateMachine and PUDI/invalid/
I know it is too late for comments on this draft, however I would like
some feedback on this subject:
The sync state machine uses PUDI/invalid/ to transition through its
states. The problem I have is that, to calculate PUDI invalid you must
practically decode the code-group. The decoder is in a different clock
domain on the other side of the lane-align block. If I use that decoder
to send a signal back to the Sync state machine I have a long round trip
delay for the data to be decoded and send back an error. Also this does
not conform to the standard since what I am decoding is an AUDI not a
PUDI. This would also cause LOS of Sync when an internal FIFO error or
Rate Adjustment error could have occured.
I have 2 thoughts on solving this.
1. Put the decoder next to the Sync StateMachine before the lane align,
and adjust the RCV statemachine accordingly.
2. Use a simplier indicator in the sync statemachine than PUDI/invalid/.
Like just Running Disparity Error.
What do you think?
Justin Gaither Phone: 512-306-7292 x529
RocketChips a Division of Xilinx Fax: 512-306-7293
500 N. Capital of TX Hwy.
Bldg 3 email: jgaither@xxxxxxxxxxxxxxx
Austin, TX 78746 WWW: www.rocketchips.com
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