sky130hd/riscv32i: tighten due to 0 tns

| Metric                                        | Old      | New      | Type     |
| ------                                        | ---      | ---      | ----     |
| detailedroute__antenna__violating__nets       |        8 |        6 | Tighten  |
| finish__timing__setup__ws                     |      0.0 |    -1.35 | Failing  |
| finish__timing__wns_percent_delay             |    -10.0 |   -31.61 | Failing  |

Signed-off-by: Matt Liberty <[email protected]>

Author: maliberty

flow/designs/sky130hd/riscv32i/config.mk

@@ -7,6 +7,5 @@ export SDC_FILE      = ./designs/$(PLATFORM)/$(DESIGN_NICKNAME)/constraint.sdc
 
 export CORE_UTILIZATION = 45
 export PLACE_DENSITY_LB_ADDON = 0.2
-export TNS_END_PERCENT = 100
 
 export REMOVE_ABC_BUFFERS = 1

flow/designs/sky130hd/riscv32i/constraint.sdc

@@ -1,6 +1,6 @@
 set clk_name  clk
 set clk_port_name clk
-set clk_period 10.0 
+set clk_period 6.0 
 set clk_io_pct 0.2
 
 set clk_port [get_ports $clk_port_name]