[PATCH v2] checkpatch: DT bindings should be a separate patch

[Rob Herring <robh@kernel.org>]

Devicetree bindings should be their own patch as documented in
Documentation/devicetree/bindings/submitting-patches.txt section I.1.
This is because bindings are logically independent from a driver
implementation, they have a different maintainer (even though they often
are applied via the same tree), and it makes for a cleaner history in
the DT only tree created with git-filter-branch.

Cc: Andy Whitcroft <apw@canonical.com>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Rob Herring <robh@kernel.org>
---
v2:
- Add doc pointer to warning
- Simplify logic

Joe, this makes $is_binding_patch an empty value when the regex doesn't 
match rather than 0 which would be more logical IMO. It seems to work 
fine, but I'm not sure if there's a better way to do it.

 scripts/checkpatch.pl | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index a9c05506e325..f9aba4bc41ce 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -2236,6 +2236,7 @@ sub process {
 	our $clean = 1;
 	my $signoff = 0;
 	my $is_patch = 0;
+	my $is_binding_patch = -1;
 	my $in_header_lines = $file ? 0 : 1;
 	my $in_commit_log = 0;		#Scanning lines before patch
 	my $has_commit_log = 0;		#Encountered lines before patch
@@ -2485,6 +2486,19 @@ sub process {
 				$check = $check_orig;
 			}
 			$checklicenseline = 1;
+
+			if ($realfile !~ /^MAINTAINERS/) {
+				my $last_binding_patch = $is_binding_patch;
+
+				$is_binding_patch = ($realfile =~ m@^(?:Documentation/devicetree/|include/dt-bindings/)@);
+
+				if (($last_binding_patch != -1) &&
+				    ($last_binding_patch ^ $is_binding_patch)) {
+					WARN("DT_SPLIT_BINDING_PATCH",
+					     "DT binding docs and includes should be a separate patch. See: Documentation/devicetree/bindings/submitting-patches.txt");
+				}
+			}
+
 			next;
 		}
 
-- 
2.17.1