regmap: debugfs: document why we don't create the debugfs entries

This is a follow-up to commit a5ba91c380b8 ("regmap: debugfs: emit a
debug message when locking is disabled"). I figured that a user may
see this message, grep the code, come to this place and he still won't
know why we actually disabled debugfs.

Add a comment explaining the reason.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/drivers/base/regmap/regmap-debugfs.c b/drivers/base/regmap/regmap-debugfs.c
index ae962b756863..f3266334063e 100644
--- a/drivers/base/regmap/regmap-debugfs.c
+++ b/drivers/base/regmap/regmap-debugfs.c
@@ -529,6 +529,13 @@ void regmap_debugfs_init(struct regmap *map, const char *name)
         struct regmap_range_node *range_node;
         const char *devname = "dummy";
 
+        /*
+         * Userspace can initiate reads from the hardware over debugfs.
+         * Normally internal regmap structures and buffers are protected with
+         * a mutex or a spinlock, but if the regmap owner decided to disable
+         * all locking mechanisms, this is no longer the case. For safety:
+         * don't create the debugfs entries if locking is disabled.
+         */
         if (map->debugfs_disable) {
                 dev_dbg(map->dev, "regmap locking disabled - not creating debugfs entries\n");
                 return;