[PATCH v5 2/7] dtc: dt-check-style: Allow space-aligning indentation in DTS

[Krzysztof Kozlowski]

DTS often have spaces after tabs in indentation for aligning continued
lines of comments or list properties, thus allow such cases to avoid
many false positives.  What we can easily detect is a space followed by
tab or too many spaces (more than alignment).

OTOH, DTS example in YAML files does not have tabs at all and there is
already rule for that, thus there is no point to check for mixed
indentation there.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxxxxxxxx>

---

Changes in v3:
1. Use re.search
2. Add dts-mixed-indent.dts test case

v2: https://lore.kernel.org/r/20260706102421.343639-4-krzysztof.kozlowski@xxxxxxxxxxxxxxxx/

Changes in v2:
1. Rework idea.
2. Adjust function doc/comment.

v1: https://lore.kernel.org/r/20260706071446.87669-2-krzysztof.kozlowski@xxxxxxxxxxxxxxxx/
---
 scripts/dtc/dt-check-style                          | 16 +++++++++++++---
 .../dtc/dt-style-selftest/bad/dts-mixed-indent.dts  | 21 +++++++++++++++++++++
 .../expected/dts-mixed-indent.dts.txt               |  9 +++++++++
 .../expected/yaml-mixed-indent.yaml.txt             |  1 -
 4 files changed, 43 insertions(+), 4 deletions(-)

diff --git a/scripts/dtc/dt-check-style b/scripts/dtc/dt-check-style
index 29b25ecf15c6..e715fb1e741c 100755
--- a/scripts/dtc/dt-check-style
+++ b/scripts/dtc/dt-check-style
@@ -359,14 +359,24 @@ def check_tab_in_yaml_example(ctx):
 
 
 def check_mixed_indent_chars(ctx):
-    """Indent must be all-spaces or all-tabs, never mixed on one line."""
+    """Indent must be all-tabs, except for aligning indentation (comments
+    or continued lines)."""
     for dl in ctx.lines:
         if not dl.indent_str:
             continue
         if dl.linetype == LineType.PREPROCESSOR:
             continue
-        if ' ' in dl.indent_str and '\t' in dl.indent_str:
+        if re.search(r' \t', dl.indent_str):
             yield (dl.lineno, 'mixed tabs and spaces in indent')
+        if dl.indent_str.count(' ') > 7:
+            yield (dl.lineno, 'too many space characters in indent (more than 7)')
+        for cont in dl.continuations:
+            if not cont.indent_str:
+                continue
+            if cont.linetype == LineType.PREPROCESSOR:
+                continue
+            if re.search(r' \t', cont.indent_str):
+                yield (cont.lineno, 'mixed tabs and spaces in indent')
 
 
 def detect_indent_unit(ctx):
@@ -932,7 +942,7 @@ RULES = [
          check_tab_in_yaml_example, applies_to=('yaml',)),
     Rule('mixed-indent-chars', 'relaxed',
          'indent must not mix tabs and spaces',
-         check_mixed_indent_chars),
+         check_mixed_indent_chars, applies_to=('dts', 'dtsi', 'dtso')),
     Rule('unclosed-block-comment', 'relaxed',
          'every /* block comment must close with */',
          check_unclosed_block_comment),
diff --git a/scripts/dtc/dt-style-selftest/bad/dts-mixed-indent.dts b/scripts/dtc/dt-style-selftest/bad/dts-mixed-indent.dts
new file mode 100644
index 000000000000..cd3de04ec5a9
--- /dev/null
+++ b/scripts/dtc/dt-style-selftest/bad/dts-mixed-indent.dts
@@ -0,0 +1,21 @@
+// SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+/* Test fixture: a .dts using wrong indent. */
+
+/dts-v1/;
+
+/ {
+	compatible = "example,test-board";
+	#address-cells = <1>;
+	#size-cells = <1>;
+
+        soc@0 {
+  		compatible = "simple-bus";
+	  	ranges = <0 0 0 0xc0000000>;
+
+		clocks = <1>,
+  			 <2>,
+			 <3>,
+		         <4>;
+		 resets = <5>;
+	};
+};
diff --git a/scripts/dtc/dt-style-selftest/expected/dts-mixed-indent.dts.txt b/scripts/dtc/dt-style-selftest/expected/dts-mixed-indent.dts.txt
new file mode 100644
index 000000000000..93146cfb51c7
--- /dev/null
+++ b/scripts/dtc/dt-style-selftest/expected/dts-mixed-indent.dts.txt
@@ -0,0 +1,9 @@
+# mode=strict
+bad/dts-mixed-indent.dts:11: [indent-consistent] indent mismatch (expected depth 1 * '\t')
+bad/dts-mixed-indent.dts:11: [mixed-indent-chars] too many space characters in indent (more than 7)
+bad/dts-mixed-indent.dts:12: [indent-consistent] indent mismatch (expected depth 2 * '\t')
+bad/dts-mixed-indent.dts:12: [mixed-indent-chars] mixed tabs and spaces in indent
+bad/dts-mixed-indent.dts:13: [indent-consistent] indent mismatch (expected depth 2 * '\t')
+bad/dts-mixed-indent.dts:13: [mixed-indent-chars] mixed tabs and spaces in indent
+bad/dts-mixed-indent.dts:16: [mixed-indent-chars] mixed tabs and spaces in indent
+bad/dts-mixed-indent.dts:19: [indent-consistent] indent mismatch (expected depth 2 * '\t')
diff --git a/scripts/dtc/dt-style-selftest/expected/yaml-mixed-indent.yaml.txt b/scripts/dtc/dt-style-selftest/expected/yaml-mixed-indent.yaml.txt
index 4b3d990e0824..bc3fc3cf00cc 100644
--- a/scripts/dtc/dt-style-selftest/expected/yaml-mixed-indent.yaml.txt
+++ b/scripts/dtc/dt-style-selftest/expected/yaml-mixed-indent.yaml.txt
@@ -1,3 +1,2 @@
 # mode=relaxed
-bad/yaml-mixed-indent.yaml:27: example 0 [mixed-indent-chars] mixed tabs and spaces in indent
 bad/yaml-mixed-indent.yaml:27: example 0 [tab-in-yaml] tab character not allowed in DTS example

-- 
2.53.0