checkpatch: DT bindings should be a separate patch

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.

[robh@kernel.org: add doc pointer to warning, simplify logic]
  Link: http://lkml.kernel.org/r/20180810170513.26284-1-robh@kernel.org
[robh@kernel.org: v3]
  Link: http://lkml.kernel.org/r/20180810225049.20452-1-robh@kernel.org
Link: http://lkml.kernel.org/r/20180809205032.22205-1-robh@kernel.org
Signed-off-by: Rob Herring <robh@kernel.org>
Acked-by: Joe Perches <joe@perches.com>
Cc: Andy Whitcroft <apw@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 14 insertions, 0 deletions

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 5971b0c11616..5219280bf7ff 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -2251,6 +2251,7 @@ sub process {
         my $author = '';
         my $authorsignoff = 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
@@ -2501,6 +2502,19 @@ 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\n");
+                                }
+                        }
+
                         next;
                 }