checkpatch: allow optional shorter config descriptions

This script is used by many other projects, and in some of them the
requirement of at least 4 line long description for all Kconfig items is
excessive.  This patch adds a command line option to control the required
minimum length.

Tested running this script over a patch including a two line config
description.  The script generated a warning when invoked as is, and did
not generate it when invoked with --min-conf-desc-length=2.
Signed-off-by: Vadim Bendebury <vbendeb@chromium.org>
Acked-by: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

scripts/checkpatch.pl

@@ -43,6 +43,7 @@ my $configuration_file = ".checkpatch.conf";
 my $max_line_length = 80;
 my $ignore_perl_version = 0;
 my $minimum_perl_version = 5.10.0;
+my $min_conf_desc_length = 4;
 
 sub help {
 	my ($exitcode) = @_;
@@ -63,6 +64,7 @@ Options:
   --types TYPE(,TYPE2...)    show only these comma separated message types
   --ignore TYPE(,TYPE2...)   ignore various comma separated message types
   --max-line-length=n        set the maximum line length, if exceeded, warn
+  --min-conf-desc-length=n   set the min description length, if shorter, warn
   --show-types               show the message "types" in the output
   --root=PATH                PATH to the kernel tree root
   --no-summary               suppress the per-file summary
@@ -131,6 +133,7 @@ GetOptions(
 	'types=s'	=> \@use,
 	'show-types!'	=> \$show_types,
 	'max-line-length=i' => \$max_line_length,
+	'min-conf-desc-length=i' => \$min_conf_desc_length,
 	'root=s'	=> \$root,
 	'summary!'	=> \$summary,
 	'mailback!'	=> \$mailback,
@@ -2285,8 +2288,10 @@ sub process {
 				}
 				$length++;
 			}
+			if ($is_start && $is_end && $length < $min_conf_desc_length) {
 				WARN("CONFIG_DESCRIPTION",
-			     "please write a paragraph that describes the config symbol fully\n" . $herecurr) if ($is_start && $is_end && $length < 4);
+				     "please write a paragraph that describes the config symbol fully\n" . $herecurr);
+			}
 			#print "is_start<$is_start> is_end<$is_end> length<$length>\n";
 		}