regmap: Fix cache defaults initialization from raw cache defaults

Currently registers with a value of 0 are ignored when initializing the register
defaults from raw defaults. This worked in the past, because registers without a
explicit default were assumed to have a default value of 0. This was changed in
commit b03622a8 ("regmap: Ensure rbtree syncs registers set to zero properly").
As a result registers, which have a raw default value of 0 are now assumed to
have no default. This again can result in unnecessary writes when syncing the
cache. It will also result in unnecessary reads for e.g. the first update
operation. In the case where readback is not possible this will even let the
update operation fail, if the register has not been written to before.

So this patch removes the check. Instead it adds a check to ignore raw defaults
for registers which are volatile, since those registers are not cached.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Cc: stable@vger.kernel.org

diff --git a/drivers/base/regmap/regcache.c b/drivers/base/regmap/regcache.c
index 1ead66186b7c0a90586f223b0b9bc23d3770a3ed..d1daa5e9fadf322b4a6e4d9e7f5d60e71eea0e40 100644 (file)
--- a/drivers/base/regmap/regcache.c
+++ b/drivers/base/regmap/regcache.c
@@ -53,7 +53,7 @@ static int regcache_hw_init(struct regmap *map)
        for (count = 0, i = 0; i < map->num_reg_defaults_raw; i++) {
                val = regcache_get_val(map->reg_defaults_raw,
                                       i, map->cache_word_size);
-               if (!val)
+               if (regmap_volatile(map, i))
                        continue;
                count++;
        }
@@ -70,7 +70,7 @@ static int regcache_hw_init(struct regmap *map)
        for (i = 0, j = 0; i < map->num_reg_defaults_raw; i++) {
                val = regcache_get_val(map->reg_defaults_raw,
                                       i, map->cache_word_size);
-               if (!val)
+               if (regmap_volatile(map, i))
                        continue;
                map->reg_defaults[j].reg = i;
                map->reg_defaults[j].def = val;