Makefile.{include,base},pkg/nanopb: fix target dependencies & code generation

Makefile.base

@@ -97,9 +97,6 @@ compile-commands: | $(DIRS:%=COMPILE-COMMANDS--%)
 	$(file >>$(BINDIR)/$(MODULE)/compile_cmds.txt,TARGET_ARCH: $(TARGET_ARCH))
 	$(file >>$(BINDIR)/$(MODULE)/compile_cmds.txt,TARGET_ARCH_LLVM: $(TARGET_ARCH_LLVM))
 
-# include makefile snippets for packages in $(PKG_PATHS) that modify GENSRC:
--include $(PKG_PATHS:%=%Makefile.gensrc)
-
 GENOBJC     := $(GENSRC:%.c=%.o)
 OBJC_LTO    := $(SRC:%.c=$(BINDIR)/$(MODULE)/%.o)
 OBJC_NOLTO  := $(SRC_NOLTO:%.c=$(BINDIR)/$(MODULE)/%.o)

Makefile.include

@@ -709,6 +709,12 @@ BUILDDEPS += $(BUILD_DIR)/CACHEDIR.TAG
 # clean removing dependencies that make previously considered as up to date.
 $(BUILDDEPS): $(CLEAN)
 
+# include makefile snippets for packages in $(PKG_PATHS) that modify GENSRC:
+-include $(PKG_PATHS:%=%Makefile.gensrc)
+# remove duplicates & make accessible to subprocesses
+GENSRC := $(sort $(GENSRC))
+export GENSRC
+
 # Save value to verify it is not modified later
 _BASELIBS_VALUE_BEFORE_USAGE := $(BASELIBS)
 
@@ -757,7 +763,7 @@ $(APPLICATION_MODULE).module: FORCE
 
 # Other modules are built by application.inc.mk and packages building
 _SUBMAKE_LIBS = $(filter-out $(APPLICATION_MODULE).module $(APPDEPS), $(BASELIBS) $(ARCHIVES))
-$(_SUBMAKE_LIBS): $(APPLICATION_MODULE).module pkg-build
+$(_SUBMAKE_LIBS): $(APPLICATION_MODULE).module pkg-build $(GENSRC)
 
 # 'print-size' triggers a rebuild. Use 'info-buildsize' if you do not need to rebuild.
 print-size: $(ELFFILE)
@@ -810,13 +816,15 @@ endif
 	@$(COLOR_ECHO)
 
 # The `clean` needs to be serialized before everything else.
-all $(BASELIBS) $(ARCHIVES) $(BUILDDEPS) ..in-docker-container: | $(CLEAN)
+all $(BASELIBS) $(ARCHIVES) $(BUILDDEPS) $(GENSRC) ..in-docker-container: | $(CLEAN)
 
 .PHONY: pkg-prepare pkg-build
 pkg-prepare:
 	-@$(foreach dir,$(PKG_PATHS),"$(MAKE)" -C $(dir) prepare $(NEWLINE))
 
-pkg-build: $(BUILDDEPS)
+$(GENSRC): pkg-prepare
+
+pkg-build: $(BUILDDEPS) | $(GENSRC)
 	$(foreach dir,$(PKG_PATHS),$(QQ)"$(MAKE)" -C $(dir) $(NEWLINE))
 
 clean:

pkg/nanopb/Makefile.gensrc

@@ -2,29 +2,40 @@ PROTOC ?= protoc
 PROTOC_GEN_NANOPB ?= $(PKGDIRBASE)/nanopb/generator/protoc-gen-nanopb
 
 PROTOBUF_FILES ?= $(wildcard *.proto)
-PROTOBUF_PATH  ?= $(CURDIR)
-GENSRC   += $(PROTOBUF_FILES:%.proto=$(BINDIR)/$(MODULE)/%.pb.c)
-GENOBJC  := $(GENSRC:%.c=%.o)
+
+# remove duplicates
+PROTOBUF_FILES := $(sort $(PROTOBUF_FILES))
+
+NANOPB_OUT_DIR := $(BINDIR)/nanopb
 
 ifneq (,$(PROTOBUF_FILES))
-  INCLUDES += -I$(BINDIR)/$(MODULE)
+  INCLUDES += -I$(NANOPB_OUT_DIR)
 endif
 
+PROTOBUF_FILES_BASENAMES = $(notdir $(PROTOBUF_FILES))
+
+GENSRC   += $(PROTOBUF_FILES_BASENAMES:%.proto=$(NANOPB_OUT_DIR)/%.pb.c)
+
 # workaround for old protoc
 PROTO_INCLUDES += -I.
 # add nanopb specific includes
 PROTO_INCLUDES += -I$(PKGDIRBASE)/nanopb/generator/proto
-PROTO_INCLUDES += -I$(PROTOBUF_PATH)
 
-$(SRC) $(SRCXX): $(GENSRC)
+# We need to filter all protobuf files for source generation as pattern
+# matching won't work due to the potentially different directory
+# prefixes.
 
-$(GENSRC): $(PROTOBUF_FILES)
-	$(Q)D=$(BINDIR)/$(MODULE) && \
-	  mkdir -p "$$D" && \
-		cd $(CURDIR) && \
-		$(MAKE) -C $(PKGDIRBASE)/nanopb/generator/proto && \
-		for protofile in $(PROTOBUF_FILES); do \
-			protoc --plugin=protoc-gen-nanopb=$(PROTOC_GEN_NANOPB) \
-				--nanopb_out="$$D" $(PROTO_INCLUDES) \
-				$^ \
-				; done
+nanopb_select_proto_from_target = $(firstword $(filter %$(notdir $(basename $(basename $(1)))).proto,$(PROTOBUF_FILES)))
+
+$(NANOPB_OUT_DIR)/%.pb.c: $(PROTOBUF_FILES)
+# We have to create the output directory here because properly chaining
+# with the clean target is currently not possible.
+	-$(Q)mkdir -p $(NANOPB_OUT_DIR)
+# Change of directory is required here because of protoc shortcomings.
+# Setting --proto_path to the same value will fail under certain
+# conditions.
+	$(Q)cd "$(dir $(call nanopb_select_proto_from_target,$@))" \
+	&& protoc --plugin=protoc-gen-nanopb=$(PROTOC_GEN_NANOPB) \
+	    --proto_path=. \
+	    --nanopb_out="$(NANOPB_OUT_DIR)" $(PROTO_INCLUDES) \
+	    $(notdir $(call nanopb_select_proto_from_target,$@))