Merge tag 'regmap-debugfs-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmap

Pull regmap debugfs optimisation fixes from Mark Brown:
 "The debugfs optimisations merged in v3.8 weren't my finest hour, there
  were a number of cases that the more complex algorithm made worse
  especially around the error handling.  This patch series should
  address those issues."

* tag 'regmap-debugfs-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmap:
  regmap: debugfs: Make sure we store the last entry in the offset cache
  regmap: debugfs: Ensure a correct return value for empty caches
  regmap: debugfs: Discard the cache if we fail to allocate an entry
  regmap: debugfs: Fix check for block start in cached seeks
  regmap: debugfs: Fix attempts to read nonexistant register blocks

drivers/base/regmap/regmap-debugfs.c

@@ -56,6 +56,19 @@ static const struct file_operations regmap_name_fops = {
 	.llseek = default_llseek,
 };
 
+static void regmap_debugfs_free_dump_cache(struct regmap *map)
+{
+	struct regmap_debugfs_off_cache *c;
+
+	while (!list_empty(&map->debugfs_off_cache)) {
+		c = list_first_entry(&map->debugfs_off_cache,
+				     struct regmap_debugfs_off_cache,
+				     list);
+		list_del(&c->list);
+		kfree(c);
+	}
+}
+
 /*
  * Work out where the start offset maps into register numbers, bearing
  * in mind that we suppress hidden registers.
@@ -91,8 +104,10 @@ static unsigned int regmap_debugfs_get_dump_start(struct regmap *map,
 			/* No cache entry?  Start a new one */
 			if (!c) {
 				c = kzalloc(sizeof(*c), GFP_KERNEL);
-				if (!c)
-					break;
+				if (!c) {
+					regmap_debugfs_free_dump_cache(map);
+					return base;
+				}
 				c->min = p;
 				c->base_reg = i;
 			}
@@ -101,14 +116,34 @@ static unsigned int regmap_debugfs_get_dump_start(struct regmap *map,
 		}
 	}
 
+	/* Close the last entry off if we didn't scan beyond it */
+	if (c) {
+		c->max = p - 1;
+		list_add_tail(&c->list,
+			      &map->debugfs_off_cache);
+	} else {
+		return base;
+	}
+
+	/*
+	 * This should never happen; we return above if we fail to
+	 * allocate and we should never be in this code if there are
+	 * no registers at all.
+	 */
+	if (list_empty(&map->debugfs_off_cache)) {
+		WARN_ON(list_empty(&map->debugfs_off_cache));
+		return base;
+	}
+
 	/* Find the relevant block */
 	list_for_each_entry(c, &map->debugfs_off_cache, list) {
-		if (*pos >= c->min && *pos <= c->max) {
+		if (from >= c->min && from <= c->max) {
 			*pos = c->min;
 			return c->base_reg;
 		}
 
-		ret = c->max;
+		*pos = c->min;
+		ret = c->base_reg;
 	}
 
 	return ret;
@@ -387,16 +422,8 @@ void regmap_debugfs_init(struct regmap *map, const char *name)
 
 void regmap_debugfs_exit(struct regmap *map)
 {
-	struct regmap_debugfs_off_cache *c;
-
 	debugfs_remove_recursive(map->debugfs);
-	while (!list_empty(&map->debugfs_off_cache)) {
-		c = list_first_entry(&map->debugfs_off_cache,
-				     struct regmap_debugfs_off_cache,
-				     list);
-		list_del(&c->list);
-		kfree(c);
-	}
+	regmap_debugfs_free_dump_cache(map);
 	kfree(map->debugfs_name);
 }