[PATCH 2/2] regmap: debugfs: Jump to the next readable register

[Lucas Tanure]

Improve the speed of the loop jumping to the next
available register

Signed-off-by: Lucas Tanure <tanur...@opensource.cirrus.com>
---
 drivers/base/regmap/regmap-debugfs.c | 27 ++++++++++++++++++++++++---
 1 file changed, 24 insertions(+), 3 deletions(-)

diff --git a/drivers/base/regmap/regmap-debugfs.c 
b/drivers/base/regmap/regmap-debugfs.c
index 9b3f49ffc4a5f..b5b1cf5aa1f96 100644
--- a/drivers/base/regmap/regmap-debugfs.c
+++ b/drivers/base/regmap/regmap-debugfs.c
@@ -190,6 +190,28 @@ static inline void regmap_calc_tot_len(struct regmap *map,
        }
 }
 
+static int regmap_next_readable_reg(struct regmap *map, int reg)
+{
+       struct regmap_debugfs_off_cache *c;
+       int ret = -EINVAL;
+
+       if (regmap_printable(map, reg + map->reg_stride)) {
+               ret = reg + map->reg_stride;
+       } else {
+               mutex_lock(&map->cache_lock);
+               list_for_each_entry(c, &map->debugfs_off_cache, list) {
+                       if (reg > c->max_reg)
+                               continue;
+                       if (reg < c->base_reg) {
+                               ret = c->base_reg;
+                               break;
+                       }
+               }
+               mutex_unlock(&map->cache_lock);
+       }
+       return ret;
+}
+
 static ssize_t regmap_read_debugfs(struct regmap *map, unsigned int from,
                                   unsigned int to, char __user *user_buf,
                                   size_t count, loff_t *ppos)
@@ -213,9 +235,8 @@ static ssize_t regmap_read_debugfs(struct regmap *map, 
unsigned int from,
        /* Work out which register we're starting at */
        start_reg = regmap_debugfs_get_dump_start(map, from, *ppos, &p);
 
-       for (i = start_reg; i <= to; i += map->reg_stride) {
-               if (!regmap_printable(map, i))
-                       continue;
+       for (i = start_reg; i >= 0 && i <= to;
+            i = regmap_next_readable_reg(map, i)) {
 
                /* If we're in the region the user is trying to read */
                if (p >= *ppos) {
-- 
2.21.0