Having a "\digit"  inside a docstring with normal strings causes
PDF output to break, as it will add a weird character inside the
string. It should be using a raw string instead.

Yet, having r"\0" won't solve, as this would be converted in
Sphinx as "0". So, this has to be inside a pre formatted text.

That's said, the comment itself is probably not the best one.

Rewrite the entire comment to properly document each parameter
and add a "delim" parameter that will be passed to the
ancillary function.

Reported-by: Akira Yokosawa <akiyks@gmail.com>
Closes: https://lore.kernel.org/linux-doc/63e99049-cc72-4156-83af-414fdde34312@gmail.com/
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
---
 tools/lib/python/kdoc/kdoc_re.py | 31 ++++++++++++++++++++-----------
 1 file changed, 20 insertions(+), 11 deletions(-)

diff --git a/tools/lib/python/kdoc/kdoc_re.py b/tools/lib/python/kdoc/kdoc_re.py
index 886e33ffd2b9..f67ebe86c458 100644
--- a/tools/lib/python/kdoc/kdoc_re.py
+++ b/tools/lib/python/kdoc/kdoc_re.py
@@ -323,19 +323,28 @@ class NestedMatch:
 
         return args
 
-    def sub(self, sub, line, count=0):
-        """
-        This is similar to re.sub:
+    def sub(self, sub, line, delim=",", count=0):
+        r"""
+        Perform a regex‑based replacement on ``line`` for all matches with
+        the ``self.regex`` pattern. It uses the following parameters:
 
-        It matches a regex that it is followed by a delimiter,
-        replacing occurrences only if all delimiters are paired.
+        ``sub``
+            Replacement string that may contain placeholders in the form
+            ``\{digit}``, where  ``digit`` is an integer referring to the regex
+            capture group number.
 
-        if r'\0' is used, it works on a similar way of using re.group(0):
-        it places the entire args of the matched paired data, with the
-        delimiter stripped.
+            ``\{0}`` is a special case that expands to the entire matched text.
 
-        If count is different than zero, it will replace at most count
-        items.
+        ``line``
+            The string to operate on.
+
+        ``delim``
+            The delimiter used by identify the placeholder groups
+            (defaults to ",").
+
+        ``count``
+            Maximum number of replacements per match.  If 0 or omitted,
+            all matches are replaced.
         """
         out = ""
 
@@ -355,7 +364,7 @@ class NestedMatch:
             # replace arguments
             new_sub = sub
             if "\\" in sub:
-                args = self._split_args(value)
+                args = self._split_args(value, delim=delim)
 
                 new_sub = re.sub(r'\\(\d+)',
                                  lambda m: args[int(m.group(1))], new_sub)
-- 
2.52.0