[U-Boot] [PATCH] fdt: Enhance dts/Makefile to be all things to all men

[Stephen Warren <swarren@wwwdotorg.org>]

On 05/28/2013 01:36 PM, Simon Glass wrote:
> There are a few partially conflicting requirements in compiling the device
> tree, since U-Boot relies on whatever is installed on the build machine.
> 
> Some versions of dtc support -i, and this is often better than using #include
> since you get correct line number information in errors.

What issue is there with line numbers when using dtc? Recent dtc
supports #line directives from the pre-processing results, and hence
reports errors in terms of the source files, just like raw dtc without cpp.

> Unfortunately this
> version must be installed manually in current Linux distributions.

Well, then that gets into the problem of some .dts files choosing to use
/include/ and rely on -i, but others using #include and not. I don't
really think it's a good idea to propagate both versions. Picking one
and using it would be far better.

I really do think we should simply require a reasonably recent dtc and
be done with it.

> Some device tree files use the word 'linux' which gets replaced with '1' by
> many version of gcc, including version 4.7. So undefine this.

Linux chose to use -undef rather than undefining specific/individual
defines. It'd be best to be consistent to that .dts files are more
likely to be portable between the two.

> diff --git a/dts/Makefile b/dts/Makefile

> +# Provide a list of include directories for dtc
> +DTS_INCS-y := -i $(SRCTREE)/arch/$(ARCH)/dts
> +
> +DTS_INCS-y += -i $(SRCTREE)/board/$(VENDOR)/dts

That has arch/ first then board/ ... (continued a few comments below)

> +DTS_INCS-$(CONFIG_CHROMEOS) += -i $(SRCTREE)/cros/dts

Is that meant to be upstream?

> +# Check if our dtc includes the -i option
> +DTS_FLAGS := $(shell if ! dtc -i 2>&1 | grep -q "invalid option"; then \
> +		echo $(DTS_INCS-y); fi)
> +
>  # We preprocess the device tree file provide a useful define
> -DTS_CPPFLAGS := -x assembler-with-cpp \
> +# Undefine 'linux' since it might be used in device tree files
> +DTS_CPPFLAGS := -x assembler-with-cpp -Ulinux \

I'll repeat my request to use -undef instead.

>  		-DARCH_CPU_DTS=\"$(SRCTREE)/arch/$(ARCH)/dts/$(CONFIG_ARCH_DEVICE_TREE).dtsi\" \
>  		-DBOARD_DTS=\"$(SRCTREE)/board/$(VENDOR)/$(BOARD)/dts/$(DEVICE_TREE).dts\" \
> -		-I$(SRCTREE)/board/$(VENDOR)/dts -I$(SRCTREE)/arch/$(ARCH)/dts
> +		-D__ASSEMBLY__ -I$(OBJTREE)/include -I$(SRCTREE)/include \
> +		-I$(OBJTREE)/include2 \

Do we really want include or include2 (what's that?) at all? The .dts
files really should be standalone, and not interact with the U-Boot
headers at all.

> +		-I$(SRCTREE)/board/$(VENDOR)/dts -I$(SRCTREE)/arch/$(ARCH)/dts \

... whereas this has board/ first then arch/. It'd be better to be
consistent.

> +		-include $(OBJTREE)/include/config.h
> +
> +DTS_TMP := $(OBJTREE)/include/generated/$(DEVICE_TREE).dts.in

Hmm. This really isn't a generated header file. Can this instead be
$(OBJTREE)/$(dir $@).$(notdir $@).dts or something like that?

> +DTS_SRC := board/$(VENDOR)/dts/$(DEVICE_TREE).dts
>  
>  all:	$(obj).depend $(LIB)
>  
> @@ -50,13 +68,19 @@ all:	$(obj).depend $(LIB)
>  # the filename.
>  DT_BIN	:= $(obj)dt.dtb
>  
> -$(DT_BIN): $(TOPDIR)/board/$(VENDOR)/dts/$(DEVICE_TREE).dts
> +DTC_CMD := $(DTC) -R 4 -p 0x1000 -O dtb -o ${DT_BIN} $(DTS_FLAGS) $(DTS_TMP)

It may be better to leave $(DTS_TMP) in the make script below, so it's
more obvious what file is being compiled; the re-direct to $(DTS_TMP) is
left in the $(CPP) invocation below, so it'd also be consistent with that.

> +$(DT_BIN): $(TOPDIR)/$(DTS_SRC)
>  	rc=$$( \
> -		cat $< | $(CPP) -P $(DTS_CPPFLAGS) - | \
> -		{ { $(DTC) -R 4 -p 0x1000 -O dtb -o ${DT_BIN} - 2>&1 ; \
> +		cat $< | $(CPP) -P $(DTS_CPPFLAGS) - > $(DTS_TMP); \
> +		{ { $(DTC_CMD)  2>&1 ; \
...

> +	if [ $$rc != 0 ]; then \
> +		echo "Source file is $(DTS_SRC)"; \
> +		echo "Compiler: $(DTC_CMD)"; \
> +	fi; \

Isn't that what make V=1 is for?