regmap: Skip hardware defaults for LZO caches

Saves some I/O when resyncing; we assume that syncs start from the device
reset state.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

diff --git a/drivers/base/regmap/regcache-lzo.c b/drivers/base/regmap/regcache-lzo.c
index b7d16143edeb19b27ffe227535afdc9a555890d5..3025cf920f255b86bae2970638e695e69ef16441 100644 (file)
--- a/drivers/base/regmap/regcache-lzo.c
+++ b/drivers/base/regmap/regcache-lzo.c
@@ -343,6 +343,12 @@ static int regcache_lzo_sync(struct regmap *map)
                ret = regcache_read(map, i, &val);
                if (ret)
                        return ret;
+
+               /* Is this the hardware default?  If so skip. */
+               ret = regcache_lookup_reg(map, i);
+               if (ret > 0 && val == map->reg_defaults[ret].def)
+                       continue;
+
                map->cache_bypass = 1;
                ret = _regmap_write(map, i, val);
                map->cache_bypass = 0;