You can now review the newly
generated suggestions and add them to the RQS file.
- Click GENERATED. The RQS_CLOCK-15 message reports high THS paths but does not provide an automatic suggestion.
- Examine RQS_CLOCK-2-1. This suggestion recommends changing the clock buffers to BUFGCE_DIV to improve the timing path uncertainty. This is a highly recommended implementation, but it cannot be automated because it requires an RTL edit. If you wish, you can make the recommendation and see the improvement, but this step can be skipped. The next steps focus on the automated suggestions.
- Click on RQS_CLOCK-1-1 to
view the detailed report. This suggestion applies CLOCK_DELAY_GROUP to related
clocks. In this report, you can see that there is a high clock skew and failing
slack.
RQS generates different suggestions at different stages of the flow. This is because the design state changes, and RQS uses the updated information to generate new suggestions. Whenever there is a change in information level, it is advisable to run
report_qor_suggestions. The following summarizes the changes as you progress through the tool flow:- Clocking estimates are accurate after
place_design. - Congestion is available after placement and improves further after routing.
- Timing estimates improve throughout the flow and are impacted by the number of paths analyzed.
- Clocking estimates are accurate after
- Click Write Suggestions. When suggestions are written, the APPLIED status is reset. All the previous suggestions and the new RQS_CLOCK-1-1 suggestion are combined into one file. You can overwrite the previous file and reuse the runs, or create a new file and new runs.
- Select the file location to overwrite the existing file. You can find out the location of this by selecting it in the sources window. Alternatively, it should be at the following location if you have followed the steps carefully: path <extract_dir>/Lab2/project_2/project_2.srcs/utils_1/imports/impl_1/rqs_report.rqs.
- Close the DCP.
- In the Design Runs window, right-click the implementation run impl_1_copy_1 and select Launch runs. When routing is complete, you can relaunch the run to see the new suggestions take effect.