From mboxrd@z Thu Jan  1 00:00:00 1970
From: Uwe =?utf-8?Q?Kleine-K=C3=B6nig?= <u.kleine-koenig-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
Subject: Bug or feature? /somenode overwrites /somenode@17 in fdt-overlay
Date: Tue, 25 Apr 2023 16:55:04 +0200
Message-ID: <20230425145504.tswuitufzikuhmnz@pengutronix.de>
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To: David Gibson <david-xT8FGy+AXnRB3Ne2BGzF6laj5H9X9Tb+@public.gmane.org>
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Hello,

TL;DR: The node &{/somenode} in my overlay overwrites &{/somenode@27}.
Is this expected?

I have the following base and overlay dts files:

	uwe@taurus:~/tmp/fdtoverlay$ cat base.dts
	/dts-v1/;

	/ {
		somenode@12 {
			property =3D <0x2a>;
		};

		somenode@27 {
			property =3D <0x20>;
		};
	};
	uwe@taurus:~/tmp/fdtoverlay$ cat overlay.dts
	/dts-v1/;
	/plugin/;

	&{/somenode} {
		property =3D <0x17>;
	};

When compiling these and using them with fdtoverlay I see that
/somenode@12 is overwritten(. And if I swap the order of /somenode@12
and /somenode@27 in base.dts, the latter is overwritten instead):

uwe@taurus:~/tmp/fdtoverlay$ dtc -I dts -O dtb -o base.dtb base.dts && dtc =
-I dts -O dtb -o overlay.dtb overlay.dts && fdtoverlay -i base.dtb -o base+=
overlay.dtb overlay.dtb && fdtdump base+overlay.dtb
base.dts:4.14-6.4: Warning (unit_address_vs_reg): /somenode@12: node has a =
unit name, but no reg or ranges property
base.dts:8.14-10.4: Warning (unit_address_vs_reg): /somenode@27: node has a=
 unit name, but no reg or ranges property

**** fdtdump is a low-level debugging tool, not meant for general use.
**** If you want to decompile a dtb, you probably want
****     dtc -I dtb -O dts <filename>

/dts-v1/;
// magic:		0xd00dfeed
// totalsize:		0x99 (153)
// off_dt_struct:	0x38
// off_dt_strings:	0x90
// off_mem_rsvmap:	0x28
// version:		17
// last_comp_version:	16
// boot_cpuid_phys:	0x0
// size_dt_strings:	0x9
// size_dt_struct:	0x58

/ {
    somenode@12 {
        property =3D <0x00000017>;
    };
    somenode@27 {
        property =3D <0x00000020>;
    };
};

I was surprised and wonder if this is as designed or if this is a bug
that should be fixed. Any insights?

Best regards
Uwe

--=20
Pengutronix e.K.                           | Uwe Kleine-K=F6nig            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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