Hello everyone. I have one question about fanout error. I used 'make user_proj_example' with original config.json. But openlane.log has fanout warning message and report as below. [WARNING]: There are max fanout violations in the design at the typical corner. Please refer to '../home/harada/Project/011_OpenLane/caravel_test_001/openlane/user_proj_example/runs/24_04_03_17_54/reports/signoff/33-rcx_sta.checks.rpt'. Pin Limit Fanout Slack --------------------------------------------------------- input37/X 16 35 -19 (VIOLATED) input39/X 16 35 -19 (VIOLATED) input40/X 16 35 -19 (VIOLATED) _157_/Y 16 32 -16 (VIOLATED) fanout124/X 16 32 -16 (VIOLATED) fanout144/X 16 32 -16 (VIOLATED) input46/X 16 32 -16 (VIOLATED) input47/X 16 32 -16 (VIOLATED) input48/X 16 29 -13 (VIOLATED) input49/X 16 29 -13 (VIOLATED) input51/X 16 26 -10 (VIOLATED) input52/X 16 26 -10 (VIOLATED) input41/X 16 23 -7 (VIOLATED) input42/X 16 23 -7 (VIOLATED) input53/X 16 23 -7 (VIOLATED) input54/X 16 23 -7 (VIOLATED) _277_/Q 16 20 -4 (VIOLATED) _289_/Q 16 20 -4 (VIOLATED) input43/X 16 20 -4 (VIOLATED) input44/X 16 20 -4 (VIOLATED) _278_/Q 16 18 -2 (VIOLATED) clkbuf_2_1_0_counter.clk/X 16 18 -2 (VIOLATED) clkbuf_2_3_0_counter.clk/X 16 18 -2 (VIOLATED) input37/X is owned by input37 instance and it is connected to 35 pins. But 34pin in 35pin are diode for ANTENNA. 〇inputs37/X instance sky130_fd_sc_hd__buf_8 input37 (.A(wb_rst_i), .VGND(vssd1), .VNB(vssd1), .VPB(vccd1), .VPWR(vccd1), .X(net37)); 〇inputs/37/x connection sky130_fd_sc_hd__diode_2 ANTENNA_360 (.DIODE(net37), sky130_fd_sc_hd__diode_2 ANTENNA_361 (.DIODE(net37), sky130_fd_sc_hd__diode_2 ANTENNA_362 (.DIODE(net37), sky130_fd_sc_hd__diode_2 ANTENNA_363 (.DIODE(net37), sky130_fd_sc_hd__diode_2 ANTENNA_364 (.DIODE(net37), sky130_fd_sc_hd__diode_2 ANTENNA_365 (.DIODE(net37), sky130_fd_sc_hd__diode_2 ANTENNA_366 (.DIODE(net37), sky130_fd_sc_hd__diode_2 ANTENNA_367 (.DIODE(net37), sky130_fd_sc_hd__diode_2 ANTENNA_368 (.DIODE(net37), sky130_fd_sc_hd__diode_2 ANTENNA_369 (.DIODE(net37), sky130_fd_sc_hd__diode_2 ANTENNA_370 (.DIODE(net37), sky130_fd_sc_hd__diode_2 ANTENNA_371 (.DIODE(net37), sky130_fd_sc_hd__diode_2 ANTENNA_372 (.DIODE(net37), sky130_fd_sc_hd__diode_2 ANTENNA_373 (.DIODE(net37), sky130_fd_sc_hd__diode_2 ANTENNA_374 (.DIODE(net37), sky130_fd_sc_hd__diode_2 ANTENNA_375 (.DIODE(net37), sky130_fd_sc_hd__diode_2 ANTENNA_376 (.DIODE(net37), sky130_fd_sc_hd__diode_2 ANTENNA_377 (.DIODE(net37), sky130_fd_sc_hd__diode_2 ANTENNA_378 (.DIODE(net37), sky130_fd_sc_hd__diode_2 ANTENNA_379 (.DIODE(net37), sky130_fd_sc_hd__diode_2 ANTENNA_380 (.DIODE(net37), sky130_fd_sc_hd__diode_2 ANTENNA_381 (.DIODE(net37), sky130_fd_sc_hd__diode_2 ANTENNA_382 (.DIODE(net37), sky130_fd_sc_hd__diode_2 ANTENNA_383 (.DIODE(net37), sky130_fd_sc_hd__diode_2 ANTENNA_384 (.DIODE(net37), sky130_fd_sc_hd__diode_2 ANTENNA_385 (.DIODE(net37), sky130_fd_sc_hd__diode_2 ANTENNA_386 (.DIODE(net37), sky130_fd_sc_hd__diode_2 ANTENNA_387 (.DIODE(net37), sky130_fd_sc_hd__diode_2 ANTENNA_388 (.DIODE(net37), sky130_fd_sc_hd__diode_2 ANTENNA_389 (.DIODE(net37), sky130_fd_sc_hd__diode_2 ANTENNA_390 (.DIODE(net37), sky130_fd_sc_hd__diode_2 ANTENNA_391 (.DIODE(net37), sky130_fd_sc_hd__diode_2 ANTENNA_392 (.DIODE(net37), sky130_fd_sc_hd__diode_2 ANTENNA__152__A_N (.DIODE(net37), sky130_fd_sc_hd__nand2b_1 152 (.A_N(net37), ANETENNA setting in config.tcl is as below. (I use original config.json for this try.) set ::env(ANTENNA_CHECK_CURRENT_DEF) "/home/harada/Project/011_OpenLane/caravel_test_001/openlane/user_proj_example/runs/24_04_03_17_54/tmp/signoff/38-user_proj_example.p.def" set ::env(ANTENNA_VIOLATOR_LIST) "/home/harada/Project/011_OpenLane/caravel_test_001/openlane/user_proj_example/runs/24_04_03_17_54/reports/signoff/43-antenna_violators.rpt" set ::env(GRT_REPAIR_ANTENNAS) "1" set ::env(HEURISTIC_ANTENNA_INSERTION_MODE) "source" set ::env(HEURISTIC_ANTENNA_THRESHOLD) "110" set ::env(USE_ARC_ANTENNA_CHECK) "1" How can I fix max fanout violation?

@Yomei Harada this might be an #openroad question. @Matt Liberty it appears that the fanout limit is being exceeded because the count includes antenna diodes. Does openroad intentionally count diodes in the fanout calculation?

Yes diodes are excluded. I'll repeat what I've said before - I don't think max fanout is useful after synthesis is over and max cap/slew should be used thereafter

@Mitch Bailey, @Matt Liberty Thank you for your answers. I understood we can ignore antenna connection to count fanout violation. I summarize the results as below. 〇How to ignore fanout violation in run_?/reports/signoff/?-rcx_sta.checks.rp (1)Count how much diodes the pins with fanout error connects. (2)Substract diode count from "Fanout" value. (3)If substracted value < "Limit" value, we can ignore. 〇Example Pin Limit Fanout Slack --------------------------------------------------------- input37/X 16 35 -19 (VIOLATED) 〇Check (1)input37/X connects 35 pins(=Fanout). (2)34/35 pins are diode from netlist. (3)35 - 34 = 1 < 16(=Limit) Fanout violation for input37/X can be ignored.