[RFC][PATCH] kbuild: Produce diff between base DT and U-Boot augmented DT if DEVICE_TREE_DEBUG=1

[RFC][PATCH] kbuild: Produce diff between base DT and U-Boot augmented DT if DEVICE_TREE_DEBUG=1

[Marek Vasut]

In case DEVICE_TREE_DEBUG is set, produce a diff between the base DT and
DT with U-Boot extras, to show how much does the U-Boot DT differ from
the base DT. This is particularly useful together with OF_UPSTREAM, to
minimize the diff between upstream DTs and U-Boot DTs.

Example usage:
$ make r8a779g3_sparrowhawk_defconfig && make DEVICE_TREE_DEBUG=1
$ cat ./dts/upstream/src/arm64/renesas/r8a779g3-sparrow-hawk.dtb.diff

This still has a downside. Even 'dtc -I dts -O dts ...' applied on
base DT and U-Boot augmented DT can produce different phandle IDs
for the same node in those two DTs, which results in a lot of noise
in the resulting diff. The only way I can think of is to patch DTC
to emit full paths in those phandles instead, something like a
phandle = <&{/full/path/to/remote/end} ...>;

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
---
Cc: Adriano Cordova <adrianox@gmail.com>
Cc: Heinrich Schuchardt <xypron.glpk@gmx.de>
Cc: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Cc: Peter Robinson <pbrobinson@gmail.com>
Cc: Sam Edwards <cfsworks@gmail.com>
Cc: Tom Rini <trini@konsulko.com>
Cc: u-boot@lists.denx.de
---
 scripts/Makefile.lib | 24 +++++++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 5db2fbc418a..2d8bf3c04f4 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -386,10 +386,31 @@ ifeq ($(CONFIG_OF_LIBFDT_OVERLAY),y)
 DTC_FLAGS += -@
 endif
 
+# In case DEVICE_TREE_DEBUG is set, produce a diff between the base DT and
+# DT with U-Boot extras, to show how much does the U-Boot DT differ from
+# the base DT. This is particularly useful together with OF_UPSTREAM, to
+# minimize the diff between upstream DTs and U-Boot DTs.
+ifdef DEVICE_TREE_DEBUG
+cmd_dtc_diff = \
+	$(HOSTCC) -E $(dtc_cpp_flags) -I$(obj) -x assembler-with-cpp -o $(dtn-tmp) $< ; \
+	$(DTC) -s -O dts -o $@.clean.dts -b 0 \
+		-i $(dir $<) $(DTC_FLAGS) $(dtn-tmp) || \
+		(echo "Check $(shell pwd)/$< for errors" && false); \
+	$(DTC) -s -O dts -o $@.full.dts -b 0 \
+		-i $(dir $<) -i $(u_boot_dtsi_loc) $(DTC_FLAGS) $(dtc-tmp) || \
+		(echo "Check $(shell pwd)/$(pre-tmp) for errors" && false); \
+	(diff -Naru $@.clean.dts $@.full.dts > $@.diff || true)
+
+dtn-tmp = $(subst $(comma),_,$(dot-target).dtn.tmp)
+else
+cmd_dtc_diff =
+endif
+
 quiet_cmd_dtc = DTC     $@
 # Modified for U-Boot
 # Bring in any U-Boot-specific include at the end of the file
 # And finally any custom .dtsi fragments specified with CONFIG_DEVICE_TREE_INCLUDES
+
 cmd_dtc = mkdir -p $(dir ${dtc-tmp}) ; \
 	(cat $< > $(pre-tmp)); \
 	$(foreach f,$(subst $(quote),,$(dtsi_include_list) $(CONFIG_DEVICE_TREE_INCLUDES)), \
@@ -400,7 +421,8 @@ cmd_dtc = mkdir -p $(dir ${dtc-tmp}) ; \
 		-d $(depfile).dtc.tmp $(dtc-tmp) || \
 		(echo "Check $(shell pwd)/$(pre-tmp) for errors" && false) \
 		; \
-	sed "s:$(pre-tmp):$(<):" $(depfile).pre.tmp $(depfile).dtc.tmp > $(depfile)
+	sed "s:$(pre-tmp):$(<):" $(depfile).pre.tmp $(depfile).dtc.tmp > $(depfile) ; \
+	$(cmd_dtc_diff)
 
 dtsi_include_list_deps := $(addprefix $(u_boot_dtsi_loc),$(subst $(quote),,$(dtsi_include_list)))
 
-- 
2.51.0

Fwd: [RFC][PATCH] kbuild: Produce diff between base DT and U-Boot augmented DT if DEVICE_TREE_DEBUG=1

[Heinrich Schuchardt]

Hello Hal, hello Minda,

Marek created the patch below, to find differences between Linux 
device-tree and what U-Boot uses.

For all JH7110 boards I find these differences which are due to 
arch/riscv/dts/starfive-visionfive2-u-boot.dtsi. Could you, please, 
check if these are still intended:

@@ -533,7 +617,7 @@
  			#clock-cells = <0x1>;
  			#reset-cells = <0x1>;
  			assigned-clock-parents = <0x28 0x0 0x28 0x2 0x28 0x2 0x3 0x59>;
-			assigned-clock-rates = <0x0 0x0 0x0 0x0 0x1dcd6500 0x59682f00>;
+			assigned-clock-rates = <0x0>;
  			assigned-clocks = <0x3 0x0 0x3 0x5 0x3 0x4 0x3 0x5a 0x3 0x1 0x28 0x0>;
  			bootph-pre-ram;
  			clock-names = "osc", "gmac1_rmii_refin", "gmac1_rgmii_rxin", 
"i2stx_bclk_ext", "i2stx_lrck_ext", "i2srx_bclk_ext", "i2srx_lrck_ext", 
"tdm_ext", "mclk_ext", "pll0_out", "pll1_out", "pll2_out";
@@ -996,6 +1080,7 @@

  		memory-controller@15700000 {
  			bootph-pre-ram;
+			clock-frequency = <0x855>; // 2133 MHz
  			clock-names = "pll";
  			clocks = <0x3 0x1>;
  			compatible = "starfive,jh7110-dmc";

Best regards

Heinrich


-------- Forwarded Message --------
Subject: [RFC][PATCH] kbuild: Produce diff between base DT and U-Boot 
augmented DT if DEVICE_TREE_DEBUG=1
Date: Thu,  6 Nov 2025 22:08:18 +0100
From: Marek Vasut <marek.vasut+renesas@mailbox.org>
To: u-boot@lists.denx.de
CC: Marek Vasut <marek.vasut+renesas@mailbox.org>, Adriano Cordova 
<adrianox@gmail.com>, Heinrich Schuchardt <xypron.glpk@gmx.de>, Ilias 
Apalodimas <ilias.apalodimas@linaro.org>, Peter Robinson 
<pbrobinson@gmail.com>, Sam Edwards <cfsworks@gmail.com>, Tom Rini 
<trini@konsulko.com>

In case DEVICE_TREE_DEBUG is set, produce a diff between the base DT and
DT with U-Boot extras, to show how much does the U-Boot DT differ from
the base DT. This is particularly useful together with OF_UPSTREAM, to
minimize the diff between upstream DTs and U-Boot DTs.

Example usage:
$ make r8a779g3_sparrowhawk_defconfig && make DEVICE_TREE_DEBUG=1
$ cat ./dts/upstream/src/arm64/renesas/r8a779g3-sparrow-hawk.dtb.diff

This still has a downside. Even 'dtc -I dts -O dts ...' applied on
base DT and U-Boot augmented DT can produce different phandle IDs
for the same node in those two DTs, which results in a lot of noise
in the resulting diff. The only way I can think of is to patch DTC
to emit full paths in those phandles instead, something like a
phandle = <&{/full/path/to/remote/end} ...>;

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
---
Cc: Adriano Cordova <adrianox@gmail.com>
Cc: Heinrich Schuchardt <xypron.glpk@gmx.de>
Cc: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Cc: Peter Robinson <pbrobinson@gmail.com>
Cc: Sam Edwards <cfsworks@gmail.com>
Cc: Tom Rini <trini@konsulko.com>
Cc: u-boot@lists.denx.de
---
  scripts/Makefile.lib | 24 +++++++++++++++++++++++-
  1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 5db2fbc418a..2d8bf3c04f4 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -386,10 +386,31 @@ ifeq ($(CONFIG_OF_LIBFDT_OVERLAY),y)
  DTC_FLAGS += -@
  endif
  +# In case DEVICE_TREE_DEBUG is set, produce a diff between the base 
DT and
+# DT with U-Boot extras, to show how much does the U-Boot DT differ from
+# the base DT. This is particularly useful together with OF_UPSTREAM, to
+# minimize the diff between upstream DTs and U-Boot DTs.
+ifdef DEVICE_TREE_DEBUG
+cmd_dtc_diff = \
+	$(HOSTCC) -E $(dtc_cpp_flags) -I$(obj) -x assembler-with-cpp -o 
$(dtn-tmp) $< ; \
+	$(DTC) -s -O dts -o $@.clean.dts -b 0 \
+		-i $(dir $<) $(DTC_FLAGS) $(dtn-tmp) || \
+		(echo "Check $(shell pwd)/$< for errors" && false); \
+	$(DTC) -s -O dts -o $@.full.dts -b 0 \
+		-i $(dir $<) -i $(u_boot_dtsi_loc) $(DTC_FLAGS) $(dtc-tmp) || \
+		(echo "Check $(shell pwd)/$(pre-tmp) for errors" && false); \
+	(diff -Naru $@.clean.dts $@.full.dts > $@.diff || true)
+
+dtn-tmp = $(subst $(comma),_,$(dot-target).dtn.tmp)
+else
+cmd_dtc_diff =
+endif
+
  quiet_cmd_dtc = DTC     $@
  # Modified for U-Boot
  # Bring in any U-Boot-specific include at the end of the file
  # And finally any custom .dtsi fragments specified with 
CONFIG_DEVICE_TREE_INCLUDES
+
  cmd_dtc = mkdir -p $(dir ${dtc-tmp}) ; \
  	(cat $< > $(pre-tmp)); \
  	$(foreach f,$(subst $(quote),,$(dtsi_include_list) 
$(CONFIG_DEVICE_TREE_INCLUDES)), \
@@ -400,7 +421,8 @@ cmd_dtc = mkdir -p $(dir ${dtc-tmp}) ; \
  		-d $(depfile).dtc.tmp $(dtc-tmp) || \
  		(echo "Check $(shell pwd)/$(pre-tmp) for errors" && false) \
  		; \
-	sed "s:$(pre-tmp):$(<):" $(depfile).pre.tmp $(depfile).dtc.tmp > 
$(depfile)
+	sed "s:$(pre-tmp):$(<):" $(depfile).pre.tmp $(depfile).dtc.tmp > 
$(depfile) ; \
+	$(cmd_dtc_diff)
   dtsi_include_list_deps := $(addprefix $(u_boot_dtsi_loc),$(subst 
$(quote),,$(dtsi_include_list)))
  -- 2.51.0

Re: [RFC][PATCH] kbuild: Produce diff between base DT and U-Boot augmented DT if DEVICE_TREE_DEBUG=1

[Heinrich Schuchardt]

On 11/6/25 22:08, Marek Vasut wrote:
> In case DEVICE_TREE_DEBUG is set, produce a diff between the base DT and
> DT with U-Boot extras, to show how much does the U-Boot DT differ from
> the base DT. This is particularly useful together with OF_UPSTREAM, to
> minimize the diff between upstream DTs and U-Boot DTs.
> 
> Example usage:
> $ make r8a779g3_sparrowhawk_defconfig && make DEVICE_TREE_DEBUG=1
> $ cat ./dts/upstream/src/arm64/renesas/r8a779g3-sparrow-hawk.dtb.diff
> 
> This still has a downside. Even 'dtc -I dts -O dts ...' applied on
> base DT and U-Boot augmented DT can produce different phandle IDs
> for the same node in those two DTs, which results in a lot of noise
> in the resulting diff. The only way I can think of is to patch DTC
> to emit full paths in those phandles instead, something like a
> phandle = <&{/full/path/to/remote/end} ...>;
> 
> Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
> ---
> Cc: Adriano Cordova <adrianox@gmail.com>
> Cc: Heinrich Schuchardt <xypron.glpk@gmx.de>
> Cc: Ilias Apalodimas <ilias.apalodimas@linaro.org>
> Cc: Peter Robinson <pbrobinson@gmail.com>
> Cc: Sam Edwards <cfsworks@gmail.com>
> Cc: Tom Rini <trini@konsulko.com>
> Cc: u-boot@lists.denx.de

Hello Marek,

Without documentation developers will not know about the new feature. 
Could you, please, add a doc/build/ change in the next iteration.

Tested-by: Heinrich Schuchardt <xypron.glpk@gmx.de>


> ---
>   scripts/Makefile.lib | 24 +++++++++++++++++++++++-
>   1 file changed, 23 insertions(+), 1 deletion(-)
> 
> diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
> index 5db2fbc418a..2d8bf3c04f4 100644
> --- a/scripts/Makefile.lib
> +++ b/scripts/Makefile.lib
> @@ -386,10 +386,31 @@ ifeq ($(CONFIG_OF_LIBFDT_OVERLAY),y)
>   DTC_FLAGS += -@
>   endif
>   
> +# In case DEVICE_TREE_DEBUG is set, produce a diff between the base DT and
> +# DT with U-Boot extras, to show how much does the U-Boot DT differ from
> +# the base DT. This is particularly useful together with OF_UPSTREAM, to
> +# minimize the diff between upstream DTs and U-Boot DTs.
> +ifdef DEVICE_TREE_DEBUG
> +cmd_dtc_diff = \
> +	$(HOSTCC) -E $(dtc_cpp_flags) -I$(obj) -x assembler-with-cpp -o $(dtn-tmp) $< ; \
> +	$(DTC) -s -O dts -o $@.clean.dts -b 0 \
> +		-i $(dir $<) $(DTC_FLAGS) $(dtn-tmp) || \
> +		(echo "Check $(shell pwd)/$< for errors" && false); \
> +	$(DTC) -s -O dts -o $@.full.dts -b 0 \
> +		-i $(dir $<) -i $(u_boot_dtsi_loc) $(DTC_FLAGS) $(dtc-tmp) || \
> +		(echo "Check $(shell pwd)/$(pre-tmp) for errors" && false); \
> +	(diff -Naru $@.clean.dts $@.full.dts > $@.diff || true)
> +
> +dtn-tmp = $(subst $(comma),_,$(dot-target).dtn.tmp)
> +else
> +cmd_dtc_diff =
> +endif
> +
>   quiet_cmd_dtc = DTC     $@
>   # Modified for U-Boot
>   # Bring in any U-Boot-specific include at the end of the file
>   # And finally any custom .dtsi fragments specified with CONFIG_DEVICE_TREE_INCLUDES
> +
>   cmd_dtc = mkdir -p $(dir ${dtc-tmp}) ; \
>   	(cat $< > $(pre-tmp)); \
>   	$(foreach f,$(subst $(quote),,$(dtsi_include_list) $(CONFIG_DEVICE_TREE_INCLUDES)), \
> @@ -400,7 +421,8 @@ cmd_dtc = mkdir -p $(dir ${dtc-tmp}) ; \
>   		-d $(depfile).dtc.tmp $(dtc-tmp) || \
>   		(echo "Check $(shell pwd)/$(pre-tmp) for errors" && false) \
>   		; \
> -	sed "s:$(pre-tmp):$(<):" $(depfile).pre.tmp $(depfile).dtc.tmp > $(depfile)
> +	sed "s:$(pre-tmp):$(<):" $(depfile).pre.tmp $(depfile).dtc.tmp > $(depfile) ; \
> +	$(cmd_dtc_diff)
>   
>   dtsi_include_list_deps := $(addprefix $(u_boot_dtsi_loc),$(subst $(quote),,$(dtsi_include_list)))
>   

Re: Fwd: [RFC][PATCH] kbuild: Produce diff between base DT and U-Boot augmented DT if DEVICE_TREE_DEBUG=1

[E Shattow]

On 11/7/25 01:00, Heinrich Schuchardt wrote:
> 
> Hello Hal, hello Minda,
> 
> Marek created the patch below, to find differences between Linux device-
> tree and what U-Boot uses.
> 
> For all JH7110 boards I find these differences which are due to arch/
> riscv/dts/starfive-visionfive2-u-boot.dtsi. Could you, please, check if
> these are still intended:
> 
> @@ -533,7 +617,7 @@
>              #clock-cells = <0x1>;
>              #reset-cells = <0x1>;
>              assigned-clock-parents = <0x28 0x0 0x28 0x2 0x28 0x2 0x3
> 0x59>;
> -            assigned-clock-rates = <0x0 0x0 0x0 0x0 0x1dcd6500
> 0x59682f00>;
> +            assigned-clock-rates = <0x0>;
>              assigned-clocks = <0x3 0x0 0x3 0x5 0x3 0x4 0x3 0x5a 0x3 0x1
> 0x28 0x0>;
>              bootph-pre-ram;
>              clock-names = "osc", "gmac1_rmii_refin",
> "gmac1_rgmii_rxin", "i2stx_bclk_ext", "i2stx_lrck_ext",
> "i2srx_bclk_ext", "i2srx_lrck_ext", "tdm_ext", "mclk_ext", "pll0_out",
> "pll1_out", "pll2_out";
> @@ -996,6 +1080,7 @@
> 
>          memory-controller@15700000 {
>              bootph-pre-ram;
> +            clock-frequency = <0x855>; // 2133 MHz
>              clock-names = "pll";
>              clocks = <0x3 0x1>;
>              compatible = "starfive,jh7110-dmc";
> 
> Best regards
> 
> Heinrich
> 
> 
> -------- Forwarded Message --------
> Subject: [RFC][PATCH] kbuild: Produce diff between base DT and U-Boot
> augmented DT if DEVICE_TREE_DEBUG=1
> Date: Thu,  6 Nov 2025 22:08:18 +0100
> From: Marek Vasut <marek.vasut+renesas@mailbox.org>
> To: u-boot@lists.denx.de
> CC: Marek Vasut <marek.vasut+renesas@mailbox.org>, Adriano Cordova
> <adrianox@gmail.com>, Heinrich Schuchardt <xypron.glpk@gmx.de>, Ilias
> Apalodimas <ilias.apalodimas@linaro.org>, Peter Robinson
> <pbrobinson@gmail.com>, Sam Edwards <cfsworks@gmail.com>, Tom Rini
> <trini@konsulko.com>
> 
> In case DEVICE_TREE_DEBUG is set, produce a diff between the base DT and
> DT with U-Boot extras, to show how much does the U-Boot DT differ from
> the base DT. This is particularly useful together with OF_UPSTREAM, to
> minimize the diff between upstream DTs and U-Boot DTs.
> 
> Example usage:
> $ make r8a779g3_sparrowhawk_defconfig && make DEVICE_TREE_DEBUG=1
> $ cat ./dts/upstream/src/arm64/renesas/r8a779g3-sparrow-hawk.dtb.diff
> 
> This still has a downside. Even 'dtc -I dts -O dts ...' applied on
> base DT and U-Boot augmented DT can produce different phandle IDs
> for the same node in those two DTs, which results in a lot of noise
> in the resulting diff. The only way I can think of is to patch DTC
> to emit full paths in those phandles instead, something like a
> phandle = <&{/full/path/to/remote/end} ...>;
> 
> Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
> ---
> Cc: Adriano Cordova <adrianox@gmail.com>
> Cc: Heinrich Schuchardt <xypron.glpk@gmx.de>
> Cc: Ilias Apalodimas <ilias.apalodimas@linaro.org>
> Cc: Peter Robinson <pbrobinson@gmail.com>
> Cc: Sam Edwards <cfsworks@gmail.com>
> Cc: Tom Rini <trini@konsulko.com>
> Cc: u-boot@lists.denx.de
> ---
>  scripts/Makefile.lib | 24 +++++++++++++++++++++++-
>  1 file changed, 23 insertions(+), 1 deletion(-)
> 
> diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
> index 5db2fbc418a..2d8bf3c04f4 100644
> --- a/scripts/Makefile.lib
> +++ b/scripts/Makefile.lib
> @@ -386,10 +386,31 @@ ifeq ($(CONFIG_OF_LIBFDT_OVERLAY),y)
>  DTC_FLAGS += -@
>  endif
>  +# In case DEVICE_TREE_DEBUG is set, produce a diff between the base DT
> and
> +# DT with U-Boot extras, to show how much does the U-Boot DT differ from
> +# the base DT. This is particularly useful together with OF_UPSTREAM, to
> +# minimize the diff between upstream DTs and U-Boot DTs.
> +ifdef DEVICE_TREE_DEBUG
> +cmd_dtc_diff = \
> +    $(HOSTCC) -E $(dtc_cpp_flags) -I$(obj) -x assembler-with-cpp -o
> $(dtn-tmp) $< ; \
> +    $(DTC) -s -O dts -o $@.clean.dts -b 0 \
> +        -i $(dir $<) $(DTC_FLAGS) $(dtn-tmp) || \
> +        (echo "Check $(shell pwd)/$< for errors" && false); \
> +    $(DTC) -s -O dts -o $@.full.dts -b 0 \
> +        -i $(dir $<) -i $(u_boot_dtsi_loc) $(DTC_FLAGS) $(dtc-tmp) || \
> +        (echo "Check $(shell pwd)/$(pre-tmp) for errors" && false); \
> +    (diff -Naru $@.clean.dts $@.full.dts > $@.diff || true)
> +
> +dtn-tmp = $(subst $(comma),_,$(dot-target).dtn.tmp)
> +else
> +cmd_dtc_diff =
> +endif
> +
>  quiet_cmd_dtc = DTC     $@
>  # Modified for U-Boot
>  # Bring in any U-Boot-specific include at the end of the file
>  # And finally any custom .dtsi fragments specified with
> CONFIG_DEVICE_TREE_INCLUDES
> +
>  cmd_dtc = mkdir -p $(dir ${dtc-tmp}) ; \
>      (cat $< > $(pre-tmp)); \
>      $(foreach f,$(subst $(quote),,$(dtsi_include_list)
> $(CONFIG_DEVICE_TREE_INCLUDES)), \
> @@ -400,7 +421,8 @@ cmd_dtc = mkdir -p $(dir ${dtc-tmp}) ; \
>          -d $(depfile).dtc.tmp $(dtc-tmp) || \
>          (echo "Check $(shell pwd)/$(pre-tmp) for errors" && false) \
>          ; \
> -    sed "s:$(pre-tmp):$(<):" $(depfile).pre.tmp $(depfile).dtc.tmp >
> $(depfile)
> +    sed "s:$(pre-tmp):$(<):" $(depfile).pre.tmp $(depfile).dtc.tmp >
> $(depfile) ; \
> +    $(cmd_dtc_diff)
>   dtsi_include_list_deps := $(addprefix $(u_boot_dtsi_loc),$(subst
> $(quote),,$(dtsi_include_list)))
>  -- 2.51.0
> 

Neither property is valid and should be removed, but the drivers need to
be fixed/implemented. For both matters please refer to discussion at:

https://lore.kernel.org/u-boot/ZQ2PR01MB13075C0C6A214EC48174F248E6F32@ZQ2PR01MB1307.CHNPR01.prod.partner.outlook.cn/

-E

Re: [RFC][PATCH] kbuild: Produce diff between base DT and U-Boot augmented DT if DEVICE_TREE_DEBUG=1

[Marek Vasut]

On 11/7/25 10:12 AM, Heinrich Schuchardt wrote:
> On 11/6/25 22:08, Marek Vasut wrote:
>> In case DEVICE_TREE_DEBUG is set, produce a diff between the base DT and
>> DT with U-Boot extras, to show how much does the U-Boot DT differ from
>> the base DT. This is particularly useful together with OF_UPSTREAM, to
>> minimize the diff between upstream DTs and U-Boot DTs.
>>
>> Example usage:
>> $ make r8a779g3_sparrowhawk_defconfig && make DEVICE_TREE_DEBUG=1
>> $ cat ./dts/upstream/src/arm64/renesas/r8a779g3-sparrow-hawk.dtb.diff
>>
>> This still has a downside. Even 'dtc -I dts -O dts ...' applied on
>> base DT and U-Boot augmented DT can produce different phandle IDs
>> for the same node in those two DTs, which results in a lot of noise
>> in the resulting diff. The only way I can think of is to patch DTC
>> to emit full paths in those phandles instead, something like a
>> phandle = <&{/full/path/to/remote/end} ...>;

What bothers me is ^ this part.

Hello Heinrich,

> Without documentation developers will not know about the new feature. 
> Could you, please, add a doc/build/ change in the next iteration.
Sure, although I am not convinced it should go in in its current form. 
Please see my first line of comment.

Re: [RFC][PATCH] kbuild: Produce diff between base DT and U-Boot augmented DT if DEVICE_TREE_DEBUG=1

[Tom Rini]

[-- Attachment #1: Type: text/plain, Size: 1532 bytes --]

On Fri, Nov 07, 2025 at 03:06:47PM +0100, Marek Vasut wrote:
> On 11/7/25 10:12 AM, Heinrich Schuchardt wrote:
> > On 11/6/25 22:08, Marek Vasut wrote:
> > > In case DEVICE_TREE_DEBUG is set, produce a diff between the base DT and
> > > DT with U-Boot extras, to show how much does the U-Boot DT differ from
> > > the base DT. This is particularly useful together with OF_UPSTREAM, to
> > > minimize the diff between upstream DTs and U-Boot DTs.
> > > 
> > > Example usage:
> > > $ make r8a779g3_sparrowhawk_defconfig && make DEVICE_TREE_DEBUG=1
> > > $ cat ./dts/upstream/src/arm64/renesas/r8a779g3-sparrow-hawk.dtb.diff
> > > 
> > > This still has a downside. Even 'dtc -I dts -O dts ...' applied on
> > > base DT and U-Boot augmented DT can produce different phandle IDs
> > > for the same node in those two DTs, which results in a lot of noise
> > > in the resulting diff. The only way I can think of is to patch DTC
> > > to emit full paths in those phandles instead, something like a
> > > phandle = <&{/full/path/to/remote/end} ...>;
> 
> What bothers me is ^ this part.
> 
> Hello Heinrich,
> 
> > Without documentation developers will not know about the new feature.
> > Could you, please, add a doc/build/ change in the next iteration.
> Sure, although I am not convinced it should go in in its current form.
> Please see my first line of comment.

Maybe we put it in the u-boot-extras repo for now as a standalone
script, so people can be asked to run it and look at the output?

-- 
Tom

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Re: [RFC][PATCH] kbuild: Produce diff between base DT and U-Boot augmented DT if DEVICE_TREE_DEBUG=1

[Marek Vasut]

On 11/7/25 4:56 PM, Tom Rini wrote:
> On Fri, Nov 07, 2025 at 03:06:47PM +0100, Marek Vasut wrote:
>> On 11/7/25 10:12 AM, Heinrich Schuchardt wrote:
>>> On 11/6/25 22:08, Marek Vasut wrote:
>>>> In case DEVICE_TREE_DEBUG is set, produce a diff between the base DT and
>>>> DT with U-Boot extras, to show how much does the U-Boot DT differ from
>>>> the base DT. This is particularly useful together with OF_UPSTREAM, to
>>>> minimize the diff between upstream DTs and U-Boot DTs.
>>>>
>>>> Example usage:
>>>> $ make r8a779g3_sparrowhawk_defconfig && make DEVICE_TREE_DEBUG=1
>>>> $ cat ./dts/upstream/src/arm64/renesas/r8a779g3-sparrow-hawk.dtb.diff
>>>>
>>>> This still has a downside. Even 'dtc -I dts -O dts ...' applied on
>>>> base DT and U-Boot augmented DT can produce different phandle IDs
>>>> for the same node in those two DTs, which results in a lot of noise
>>>> in the resulting diff. The only way I can think of is to patch DTC
>>>> to emit full paths in those phandles instead, something like a
>>>> phandle = <&{/full/path/to/remote/end} ...>;
>>
>> What bothers me is ^ this part.
>>
>> Hello Heinrich,
>>
>>> Without documentation developers will not know about the new feature.
>>> Could you, please, add a doc/build/ change in the next iteration.
>> Sure, although I am not convinced it should go in in its current form.
>> Please see my first line of comment.
> 
> Maybe we put it in the u-boot-extras repo for now as a standalone
> script, so people can be asked to run it and look at the output?
I'd say no, because the output is full of noise unless the phandle 
non-resolution gets somehow improved.

Re: [RFC][PATCH] kbuild: Produce diff between base DT and U-Boot augmented DT if DEVICE_TREE_DEBUG=1

[Marek Vasut]

On 11/7/25 5:44 PM, Marek Vasut wrote:
> On 11/7/25 4:56 PM, Tom Rini wrote:
>> On Fri, Nov 07, 2025 at 03:06:47PM +0100, Marek Vasut wrote:
>>> On 11/7/25 10:12 AM, Heinrich Schuchardt wrote:
>>>> On 11/6/25 22:08, Marek Vasut wrote:
>>>>> In case DEVICE_TREE_DEBUG is set, produce a diff between the base 
>>>>> DT and
>>>>> DT with U-Boot extras, to show how much does the U-Boot DT differ from
>>>>> the base DT. This is particularly useful together with OF_UPSTREAM, to
>>>>> minimize the diff between upstream DTs and U-Boot DTs.
>>>>>
>>>>> Example usage:
>>>>> $ make r8a779g3_sparrowhawk_defconfig && make DEVICE_TREE_DEBUG=1
>>>>> $ cat ./dts/upstream/src/arm64/renesas/r8a779g3-sparrow-hawk.dtb.diff
>>>>>
>>>>> This still has a downside. Even 'dtc -I dts -O dts ...' applied on
>>>>> base DT and U-Boot augmented DT can produce different phandle IDs
>>>>> for the same node in those two DTs, which results in a lot of noise
>>>>> in the resulting diff. The only way I can think of is to patch DTC
>>>>> to emit full paths in those phandles instead, something like a
>>>>> phandle = <&{/full/path/to/remote/end} ...>;
>>>
>>> What bothers me is ^ this part.
>>>
>>> Hello Heinrich,
>>>
>>>> Without documentation developers will not know about the new feature.
>>>> Could you, please, add a doc/build/ change in the next iteration.
>>> Sure, although I am not convinced it should go in in its current form.
>>> Please see my first line of comment.
>>
>> Maybe we put it in the u-boot-extras repo for now as a standalone
>> script, so people can be asked to run it and look at the output?
> I'd say no, because the output is full of noise unless the phandle non- 
> resolution gets somehow improved.

If I run this with "DTC=/usr/bin/dtc make ..." , then the phandles are 
correctly retained. This uses system DTC 1.7.2 instead of in-tree DTC 
1.4.6+ .

Is there still any reason for us to carry our own copy of DTC ?

Re: [RFC][PATCH] kbuild: Produce diff between base DT and U-Boot augmented DT if DEVICE_TREE_DEBUG=1

[Tom Rini]

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On Mon, Nov 10, 2025 at 12:44:31AM +0100, Marek Vasut wrote:
> On 11/7/25 5:44 PM, Marek Vasut wrote:
> > On 11/7/25 4:56 PM, Tom Rini wrote:
> > > On Fri, Nov 07, 2025 at 03:06:47PM +0100, Marek Vasut wrote:
> > > > On 11/7/25 10:12 AM, Heinrich Schuchardt wrote:
> > > > > On 11/6/25 22:08, Marek Vasut wrote:
> > > > > > In case DEVICE_TREE_DEBUG is set, produce a diff between
> > > > > > the base DT and
> > > > > > DT with U-Boot extras, to show how much does the U-Boot DT differ from
> > > > > > the base DT. This is particularly useful together with OF_UPSTREAM, to
> > > > > > minimize the diff between upstream DTs and U-Boot DTs.
> > > > > > 
> > > > > > Example usage:
> > > > > > $ make r8a779g3_sparrowhawk_defconfig && make DEVICE_TREE_DEBUG=1
> > > > > > $ cat ./dts/upstream/src/arm64/renesas/r8a779g3-sparrow-hawk.dtb.diff
> > > > > > 
> > > > > > This still has a downside. Even 'dtc -I dts -O dts ...' applied on
> > > > > > base DT and U-Boot augmented DT can produce different phandle IDs
> > > > > > for the same node in those two DTs, which results in a lot of noise
> > > > > > in the resulting diff. The only way I can think of is to patch DTC
> > > > > > to emit full paths in those phandles instead, something like a
> > > > > > phandle = <&{/full/path/to/remote/end} ...>;
> > > > 
> > > > What bothers me is ^ this part.
> > > > 
> > > > Hello Heinrich,
> > > > 
> > > > > Without documentation developers will not know about the new feature.
> > > > > Could you, please, add a doc/build/ change in the next iteration.
> > > > Sure, although I am not convinced it should go in in its current form.
> > > > Please see my first line of comment.
> > > 
> > > Maybe we put it in the u-boot-extras repo for now as a standalone
> > > script, so people can be asked to run it and look at the output?
> > I'd say no, because the output is full of noise unless the phandle non-
> > resolution gets somehow improved.
> 
> If I run this with "DTC=/usr/bin/dtc make ..." , then the phandles are
> correctly retained. This uses system DTC 1.7.2 instead of in-tree DTC 1.4.6+
> .
> 
> Is there still any reason for us to carry our own copy of DTC ?

I think the answers last time came down to needing to first re-sync the
dtc flags with upstream kernel again (to ignore new things that won't be
fixed), then possibly fixing at least any big scary warnings that do
exist, and then we can just document and use host dtc. Dealing with
pylibfdt may have been its own issue as well.

-- 
Tom

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Re: [RFC][PATCH] kbuild: Produce diff between base DT and U-Boot augmented DT if DEVICE_TREE_DEBUG=1

[Marek Vasut]

On 11/10/25 5:47 PM, Tom Rini wrote:
> On Mon, Nov 10, 2025 at 12:44:31AM +0100, Marek Vasut wrote:
>> On 11/7/25 5:44 PM, Marek Vasut wrote:
>>> On 11/7/25 4:56 PM, Tom Rini wrote:
>>>> On Fri, Nov 07, 2025 at 03:06:47PM +0100, Marek Vasut wrote:
>>>>> On 11/7/25 10:12 AM, Heinrich Schuchardt wrote:
>>>>>> On 11/6/25 22:08, Marek Vasut wrote:
>>>>>>> In case DEVICE_TREE_DEBUG is set, produce a diff between
>>>>>>> the base DT and
>>>>>>> DT with U-Boot extras, to show how much does the U-Boot DT differ from
>>>>>>> the base DT. This is particularly useful together with OF_UPSTREAM, to
>>>>>>> minimize the diff between upstream DTs and U-Boot DTs.
>>>>>>>
>>>>>>> Example usage:
>>>>>>> $ make r8a779g3_sparrowhawk_defconfig && make DEVICE_TREE_DEBUG=1
>>>>>>> $ cat ./dts/upstream/src/arm64/renesas/r8a779g3-sparrow-hawk.dtb.diff
>>>>>>>
>>>>>>> This still has a downside. Even 'dtc -I dts -O dts ...' applied on
>>>>>>> base DT and U-Boot augmented DT can produce different phandle IDs
>>>>>>> for the same node in those two DTs, which results in a lot of noise
>>>>>>> in the resulting diff. The only way I can think of is to patch DTC
>>>>>>> to emit full paths in those phandles instead, something like a
>>>>>>> phandle = <&{/full/path/to/remote/end} ...>;
>>>>>
>>>>> What bothers me is ^ this part.
>>>>>
>>>>> Hello Heinrich,
>>>>>
>>>>>> Without documentation developers will not know about the new feature.
>>>>>> Could you, please, add a doc/build/ change in the next iteration.
>>>>> Sure, although I am not convinced it should go in in its current form.
>>>>> Please see my first line of comment.
>>>>
>>>> Maybe we put it in the u-boot-extras repo for now as a standalone
>>>> script, so people can be asked to run it and look at the output?
>>> I'd say no, because the output is full of noise unless the phandle non-
>>> resolution gets somehow improved.
>>
>> If I run this with "DTC=/usr/bin/dtc make ..." , then the phandles are
>> correctly retained. This uses system DTC 1.7.2 instead of in-tree DTC 1.4.6+
>> .
>>
>> Is there still any reason for us to carry our own copy of DTC ?
> 
> I think the answers last time came down to needing to first re-sync the
> dtc flags with upstream kernel again (to ignore new things that won't be
> fixed), then possibly fixing at least any big scary warnings that do
> exist, and then we can just document and use host dtc. Dealing with
> pylibfdt may have been its own issue as well.
Let's see if I can get anywhere with DTC 1.7.2 full sync, I already have 
a prototype.

Re: [RFC][PATCH] kbuild: Produce diff between base DT and U-Boot augmented DT if DEVICE_TREE_DEBUG=1

[Simon Glass]

Hi Marek,

On Fri, 7 Nov 2025 at 17:44, Marek Vasut <marek.vasut@mailbox.org> wrote:
>
> On 11/7/25 4:56 PM, Tom Rini wrote:
> > On Fri, Nov 07, 2025 at 03:06:47PM +0100, Marek Vasut wrote:
> >> On 11/7/25 10:12 AM, Heinrich Schuchardt wrote:
> >>> On 11/6/25 22:08, Marek Vasut wrote:
> >>>> In case DEVICE_TREE_DEBUG is set, produce a diff between the base DT and
> >>>> DT with U-Boot extras, to show how much does the U-Boot DT differ from
> >>>> the base DT. This is particularly useful together with OF_UPSTREAM, to
> >>>> minimize the diff between upstream DTs and U-Boot DTs.
> >>>>
> >>>> Example usage:
> >>>> $ make r8a779g3_sparrowhawk_defconfig && make DEVICE_TREE_DEBUG=1
> >>>> $ cat ./dts/upstream/src/arm64/renesas/r8a779g3-sparrow-hawk.dtb.diff
> >>>>
> >>>> This still has a downside. Even 'dtc -I dts -O dts ...' applied on
> >>>> base DT and U-Boot augmented DT can produce different phandle IDs
> >>>> for the same node in those two DTs, which results in a lot of noise
> >>>> in the resulting diff. The only way I can think of is to patch DTC
> >>>> to emit full paths in those phandles instead, something like a
> >>>> phandle = <&{/full/path/to/remote/end} ...>;
> >>
> >> What bothers me is ^ this part.
> >>
> >> Hello Heinrich,
> >>
> >>> Without documentation developers will not know about the new feature.
> >>> Could you, please, add a doc/build/ change in the next iteration.
> >> Sure, although I am not convinced it should go in in its current form.
> >> Please see my first line of comment.
> >
> > Maybe we put it in the u-boot-extras repo for now as a standalone
> > script, so people can be asked to run it and look at the output?
> I'd say no, because the output is full of noise unless the phandle
> non-resolution gets somehow improved.

Another idea would be to create an fdtdiff tool which does this. We
already have fdtgrep[1]

Regards,
Simon

[1] https://github.com/devicetree-org/fdt-tools

Re: [RFC][PATCH] kbuild: Produce diff between base DT and U-Boot augmented DT if DEVICE_TREE_DEBUG=1

[Marek Vasut]

On 11/11/25 1:38 PM, Simon Glass wrote:

Hello Simon,

>>> Maybe we put it in the u-boot-extras repo for now as a standalone
>>> script, so people can be asked to run it and look at the output?
>> I'd say no, because the output is full of noise unless the phandle
>> non-resolution gets somehow improved.
> 
> Another idea would be to create an fdtdiff tool which does this. We
> already have fdtgrep[1]

A new tool is not needed, up to date DTC retains the phandles across dtc 
-I dts -O dts and the result can be diff'd using regular diff.

-- 
Best regards,
Marek Vasut

Re: [RFC][PATCH] kbuild: Produce diff between base DT and U-Boot augmented DT if DEVICE_TREE_DEBUG=1

[Simon Glass]

Hi Marek,

On Tue, 11 Nov 2025 at 08:26, Marek Vasut <marek.vasut@mailbox.org> wrote:
>
> On 11/11/25 1:38 PM, Simon Glass wrote:
>
> Hello Simon,
>
> >>> Maybe we put it in the u-boot-extras repo for now as a standalone
> >>> script, so people can be asked to run it and look at the output?
> >> I'd say no, because the output is full of noise unless the phandle
> >> non-resolution gets somehow improved.
> >
> > Another idea would be to create an fdtdiff tool which does this. We
> > already have fdtgrep[1]
>
> A new tool is not needed, up to date DTC retains the phandles across dtc
> -I dts -O dts and the result can be diff'd using regular diff.

That's good! Sounds like it was a bug.

Regards,
Simon