[PATCH 0/6] Restore phandles from binary representations

Hello,

this is a followup to https://github.com/dgibson/dtc/pull/151, but I
switched to submission by mail because the workflow is (at least
subjectively for me) better suited for such a big and long living patch
set. Parts of the patches discussed on github were already applied.

Sample output to show the benefit:

	$ cat a.dts
	/dts-v1/;

	/ {
		node1 {
			node2 = <&node2>;
		};

		node2: node2 {
			property = "somevalue";
		};
	};

	$ cat b.dts
	/dts-v1/;

	/ {
		node0: node0 {
			self = <&node0>;
		};

		node1 {
			node2 = <&node2>;
		};

		node2: node2 {
			property = "somevalue";
		};
	};


So b.dts just added a node0 over a.dts, node1 and node2 didn't change at
all.

	$ dtc -L -@ a.dts > a.dtb
	$ dtc -L -@ b.dts > b.dtb

Now using dtc without this patch set I get:

	$ dtdiff a.dtb b.dtb
	--- /dev/fd/63	2025-08-20 14:55:37.253413183 +0200
	+++ /dev/fd/62	2025-08-20 14:55:37.253413183 +0200
	@@ -4,21 +4,31 @@
	 
		__local_fixups__ {
	 
	+		node0 {
	+			self = <0x00>;
	+		};
	+
			node1 {
				node2 = <0x00>;
			};
		};
	 
		__symbols__ {
	+		node0 = "/node0";
			node2 = "/node2";
		};
	 
	+	node0 {
	+		phandle = <0x01>;
	+		self = <0x01>;
	+	};
	+
		node1 {
	-		node2 = <0x01>;
	+		node2 = <0x02>;
		};
	 
		node2 {
	-		phandle = <0x01>;
	+		phandle = <0x02>;
			property = "somevalue";
		};
	 };

With this series applied the output becomes:

	$ dtdiff a.dtb b.dtb
	--- /dev/fd/63	2025-08-20 14:56:02.585884273 +0200
	+++ /dev/fd/62	2025-08-20 14:56:02.589884347 +0200
	@@ -5,21 +5,31 @@
	 
		__local_fixups__ {
	 
	+		node0 {
	+			self = <0x00>;
	+		};
	+
			node1 {
				node2 = <0x00>;
			};
		};
	 
		__symbols__ {
	+		node0 = "/node0";
			node2 = "/node2";
		};
	 
	+	node0: node0 {
	+		phandle = <0x01>;
	+		self = <&node0>;
	+	};
	+
		node1 {
			node2 = <&node2>;
		};
	 
		node2: node2 {
	-		phandle = <0x01>;
	+		phandle = <0x02>;
			property = "somevalue";
		};
	 };

The relevant difference here is that the renumbering of phandles that
affects /node2 doesn't result in noise in /node1, so it's easily visible
that /node1/node2 still points to the same node that just got a new
phandle value.

In this minimal example the signal to noise ratio is bad, with bigger
device trees the improvement is much more relevant. (Think 50 nodes that
are not affected by renumbering and the noise being concentrated to
__local_fixups__, __fixups__ and the changes of the actual phandle
properties but not their usage.)

Best regards
Uwe

Uwe Kleine-König (6):
  Emit /plugin/ when compiling to .dts with DTSF_PLUGIN set
  Set DTSF_PLUGIN if needed when compiling from dtb
  Improve type guessing when compiling to dts format
  Restore labels from __symbols__ node
  Restore phandle references from __local_fixups__ node
  Restore phandle references from __fixups__ node

 dtc.c        |   5 ++
 dtc.h        |   6 ++
 flattree.c   |   6 +-
 livetree.c   | 174 +++++++++++++++++++++++++++++++++++++++++++++++++++
 treesource.c | 114 ++++++++++++++++++++++++---------
 5 files changed, 273 insertions(+), 32 deletions(-)


base-commit: e1284ee5dc20f94097bc6424ede9c3e433dba77d
-- 
2.50.1