From mboxrd@z Thu Jan  1 00:00:00 1970
From: Frank Rowand <frowand.list-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Subject: case sensitivity for devicetree node names
Date: Fri, 10 Jun 2016 13:05:24 -0700
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To: Rob Herring <robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org>, David Gibson <david-xT8FGy+AXnRB3Ne2BGzF6laj5H9X9Tb+@public.gmane.org>, "devicetree-spec-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" <devicetree-spec-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" <devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>

I had assumed that devicetree node names were case sensitive. But a recent
email thread asserted that they were not, which made me curious.

dtc treats node names as case sensitive:

$ cat test_node_case_1.dts

/dts-v1/;

/ {
	node-x {
		prop_a = < 1 >;
	};
};

/ {
	node-X {
		prop_a = < 2 >;
	};
};

$ cat test_node_case_2.dts

/dts-v1/;

/ {
	node-x {
		prop_a = < 1 >;
	};
};

/ {
	node-x {
		prop_a = < 2 >;
	};
};

$ dtc -O dts test_node_case_1.dts
/dts-v1/;

/ {

	node-x {
		prop_a = <0x1>;
	};

	node-X {
		prop_a = <0x2>;
	};
};

$ dtc -O dts test_node_case_2.dts
/dts-v1/;

/ {

	node-x {
		prop_a = <0x2>;
	};
};


But the Linux kernel source code defines of_node_cmp() as:

  include/linux/of.h:

  /* Default string compare functions, Allow arch asm/prom.h to override */
  #if !defined(of_compat_cmp)
  #define of_node_cmp(s1, s2) strcasecmp((s1), (s2))

arch/sparc/include/asm/prom.h uses strcmp() instead of strcasecmp().

Examples of using of_node_cmp() to check for a node name can be found,
for example, of_find_node_by_name().

Is case insensitivity for node names a bug in the Linux kernel, or desired
for some reason?

-Frank