gateware/icE1usb: Add custom pre-pack optimizations to fix build
Without theses there are too many control-sets generated by yosys and
nextpnr can't find any valid placement.
Signed-off-by: Sylvain Munaut <tnt@246tNt.com>
diff --git a/gateware/icE1usb/Makefile b/gateware/icE1usb/Makefile
index 2d70f72..2bfd1b5 100644
--- a/gateware/icE1usb/Makefile
+++ b/gateware/icE1usb/Makefile
@@ -36,9 +36,9 @@
DEVICE := up5k
PACKAGE := sg48
-YOSYS_SYNTH_ARGS = -dffe_min_ce_use 4
SEED ?= 15
-NEXTPNR_ARGS := --no-promote-globals --pre-pack data/clocks.py --seed $(SEED)
+YOSYS_SYNTH_ARGS :=
+NEXTPNR_ARGS := --pre-pack data/clocks.py --pre-pack data/opt.py --seed $(SEED)
ifeq ($(IGNORE_TIMING),1)
NEXTPNR_ARGS += --timing-allow-fail