[PATCH] 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>
---
 scripts/checkpatch.pl | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index a9c05506e325..20547c109ccd 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 +2486,27 @@ sub process {
 				$check = $check_orig;
 			}
 			$checklicenseline = 1;
+
+			if ($realfile !~ /MAINTAINERS/) {
+				my $mixed = 0;
+				if ($realfile =~ /(Documentation\/devicetree|include\/dt-bindings).*/) {
+					if ($is_binding_patch == 0) {
+						$mixed = 1;
+					}
+					$is_binding_patch = 1;
+				} else {
+					if ($is_binding_patch == 1) {
+						$mixed = 1;
+					}
+					$is_binding_patch = 0;
+				}
+
+				if ($mixed == 1) {
+					WARN("DT_SPLIT_BINDING_PATCH",
+					     "DT binding docs and includes should be a separate patch\n");
+				}
+			}
+
 			next;
 		}
 
-- 
2.17.1