1 files changed, 23 insertions, 4 deletions

diff --git a/drivers/base/regmap/regcache-rbtree.c b/drivers/base/regmap/regcache-rbtree.c
index 32620c4f1683..8d51916a283d 100644
--- a/drivers/base/regmap/regcache-rbtree.c
+++ b/drivers/base/regmap/regcache-rbtree.c
@@ -357,7 +357,8 @@ static int regcache_rbtree_write(struct regmap *map, unsigned int reg,
         return 0;
 }
 
-static int regcache_rbtree_sync(struct regmap *map)
+static int regcache_rbtree_sync(struct regmap *map, unsigned int min,
+                                unsigned int max)
 {
         struct regcache_rbtree_ctx *rbtree_ctx;
         struct rb_node *node;
@@ -365,19 +366,37 @@ static int regcache_rbtree_sync(struct regmap *map)
         unsigned int regtmp;
         unsigned int val;
         int ret;
-        int i;
+        int i, base, end;
 
         rbtree_ctx = map->cache;
         for (node = rb_first(&rbtree_ctx->root); node; node = rb_next(node)) {
                 rbnode = rb_entry(node, struct regcache_rbtree_node, node);
-                for (i = 0; i < rbnode->blklen; i++) {
+
+                if (rbnode->base_reg < min)
+                        continue;
+                if (rbnode->base_reg > max)
+                        break;
+                if (rbnode->base_reg + rbnode->blklen < min)
+                        continue;
+
+                if (min > rbnode->base_reg)
+                        base = min - rbnode->base_reg;
+                else
+                        base = 0;
+
+                if (max < rbnode->base_reg + rbnode->blklen)
+                        end = rbnode->base_reg + rbnode->blklen - max;
+                else
+                        end = rbnode->blklen;
+
+                for (i = base; i < end; i++) {
                         regtmp = rbnode->base_reg + i;
                         val = regcache_rbtree_get_register(rbnode, i,
                                                            map->cache_word_size);
 
                         /* Is this the hardware default?  If so skip. */
                         ret = regcache_lookup_reg(map, i);
-                        if (ret > 0 && val == map->reg_defaults[ret].def)
+                        if (ret >= 0 && val == map->reg_defaults[ret].def)
                                 continue;
 
                         map->cache_bypass = 1;