Solution

000035447 - Design Advisory - 2023.1.x (and prior) Vivado and Versal - timing of bypass BLI setup path and BUFGCTRL cascade are incorrect

Release Date
2023-10-19
Revision
1.0 English

Both of these issues are resolved in the 2023.2 Vivado release.

 

Timing of bypass BLI setup path


The Memory Controllers are not impacted as they do not bypass the BLI. If you are using the BLI in these paths, you are not impacted. You will also not be impacted if there is sufficient margin in your setup of the impacted paths.

To assess if your design is impacted please run the attached script.

source BLI_Route_Thru_Slack_Adjust.tcl -quiet
BLI_Route_Thru_Setup_Margin_Fix 0.25

If there are no paths exposed to this issue the script will report the following:

   #######  ##    ##
  ##     ## ##   ##
  ##     ## ##  ##
  ##     ## #####
  ##     ## ##  ##
  ##     ## ##   ##
   #######  ##    ##

INFO: Design does not contain any pins that will have to be checked for slack. All the pin in this design are safely timed. Skipping timing check and re-route

If a path is impacted, the script will then add a max delay on the impacted path, un-route and re-route the net, and rerun timing.

 

If the path is able to fix the issue it will report the following:

  ##      ##    ###    ########  ##    ## #### ##    ##  ######
  ##  ##  ##   ## ##   ##     ## ###   ##  ##  ###   ## ##    ##
  ##  ##  ##  ##   ##  ##     ## ####  ##  ##  ####  ## ##
  ##  ##  ## ##     ## ########  ## ## ##  ##  ## ## ## ##   ####
  ##  ##  ## ######### ##   ##   ##  ####  ##  ##  #### ##    ##
  ##  ##  ## ##     ## ##    ##  ##   ###  ##  ##   ### ##    ##
   ###  ###  ##     ## ##     ## ##    ## #### ##    ##  ######

INFO: Un-route and re-route has been completed successfully for all candidate pins. All pins in the design meet the new slack requirement.

If the script is unable to fix the issue it will report the one of the following:

  ##      ##    ###    ########  ##    ## #### ##    ##  ######
  ##  ##  ##   ## ##   ##     ## ###   ##  ##  ###   ## ##    ##
  ##  ##  ##  ##   ##  ##     ## ####  ##  ##  ####  ## ##
  ##  ##  ## ##     ## ########  ## ## ##  ##  ## ## ## ##   ####
  ##  ##  ## ######### ##   ##   ##  ####  ##  ##  #### ##    ##
  ##  ##  ## ##     ## ##    ##  ##   ###  ##  ##   ### ##    ##
   ###  ###  ##     ## ##     ## ##    ## #### ##    ##  ######
WARNING: Data path delay to pin has improved after un-routing and re-routing the associated net with set_max_delay constraints but it is still lesser than the specified margin. This could be a result of congestion, placement or different router priority. If it is congestion or placement related, try un-routing and un-placing the design followed by place and route. If it is due to routing priority, try unrouting and re-routing the design to see if the pins meet the required slack
  ##      ##    ###    ########  ##    ## #### ##    ##  ######
  ##  ##  ##   ## ##   ##     ## ###   ##  ##  ###   ## ##    ##
  ##  ##  ##  ##   ##  ##     ## ####  ##  ##  ####  ## ##
  ##  ##  ## ##     ## ########  ## ## ##  ##  ## ## ## ##   ####
  ##  ##  ## ######### ##   ##   ##  ####  ##  ##  #### ##    ##
  ##  ##  ## ##     ## ##    ##  ##   ###  ##  ##   ### ##    ##
   ###  ###  ##     ## ##     ## ##    ## #### ##    ##  ######
WARNING: Data path delay to pin has either degraded or remained the same after un-routing and re-routing the associated net with set_max_delay constraints. This could be a result of congestion, placement or different router priority. If it is congestion or placement related, try un-routing and un-placing the design followed by place and route. If it is due to routing priority, try unrouting and re-routing the design to see if the pins meet the required slack.
 

If there are issues meeting timing using the script, please contact Technical Support.


Note: All Versal device families and speed grades are impacted, except for the Versal HBM production devices in Vivado 2022.1.2 which are not impacted.

Timing of BUFGCTRL Cascade
 

To assess if your design is impacted, please run the attached BUFGCTRL_Cascade_Detect.tcl script. 

source  BUFGCTRL_Cascade_Detection.tcl  -quiet
BUFGCTRL_Cascade_Detect
 

If there are no paths exposed to this issue the script will report the following:

INFO: Design does not contain any BUFGCTRL cascades
 

If there are issues in the design found with the script it will report the following:

WARNING: Design contains BUFGCTRL cascades. Timing through the cascade may not be accurate.

If there are issues flagged by the script and you cannot retime in Vivado 2023.2, please contact Technical Support.