Fix ChibiOS FPU build logic (#9132)

tmk_core/chibios.mk

@@ -220,6 +220,18 @@ COMPILEFLAGS += -fno-common
 COMPILEFLAGS += -fshort-wchar
 COMPILEFLAGS += $(THUMBFLAGS)
 
+# FPU options default (Cortex-M4 and Cortex-M7 single precision).
+USE_FPU_OPT ?= -mfloat-abi=hard -mfpu=fpv4-sp-d16 -fsingle-precision-constant
+
+# FPU-related options
+USE_FPU ?= no
+ifneq ($(USE_FPU),no)
+  COMPILEFLAGS += $(USE_FPU_OPT)
+  OPT_DEFS += -DCORTEX_USE_FPU=TRUE
+else
+  OPT_DEFS += -DCORTEX_USE_FPU=FALSE
+endif
+
 CFLAGS += $(COMPILEFLAGS)
 
 ASFLAGS += $(THUMBFLAGS)
@@ -241,22 +253,6 @@ OPT_DEFS += -DPORT_IGNORE_GCC_VERSION_CHECK=1
 
 MCUFLAGS = -mcpu=$(MCU)
 
-# FPU options default (Cortex-M4 and Cortex-M7 single precision).
-ifeq ($(USE_FPU_OPT),)
-  USE_FPU_OPT = -mfloat-abi=$(USE_FPU) -mfpu=fpv4-sp-d16 -fsingle-precision-constant
-endif
-
-# FPU-related options
-ifeq ($(USE_FPU),)
-  USE_FPU = no
-endif
-ifneq ($(USE_FPU),no)
-  OPT    += $(USE_FPU_OPT)
-  OPT_DEFS  += -DCORTEX_USE_FPU=TRUE
-else
-  OPT_DEFS  += -DCORTEX_USE_FPU=FALSE
-endif
-
 DEBUG = gdb
 
 DFU_ARGS ?=

tmk_core/rules.mk

@@ -46,7 +46,7 @@ FORMAT = ihex
 # Optimization level, can be [0, 1, 2, 3, s].
 #     0 = turn off optimization. s = optimize for size.
 #     (Note: 3 is not always the best optimization level. See avr-libc FAQ.)
-OPT = s
+OPT ?= s
 
 # Compiler flag to set the C Standard level.
 #     c89   = "ANSI" C