regmap: Allow caches for devices with no defaults

We only really need the defaults in order to cut down the number of
registers we sync and to satisfy reads while the device is powered off
but not all devices are going to need to do that (always on devices like
PMICs being the prime example) so don't require those devices to supply
a default.  Instead only try to fall back to hardware defaults if the
driver told us to.

Devices using LZO won't be able to instantiate with this, that will require
some updates in the LZO code to handle this case.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Dimitris Papastamos <dp@opensource.wolfsonmicro.com>

diff --git a/drivers/base/regmap/regcache.c b/drivers/base/regmap/regcache.c
index 409abd282c6c90e9684719b8522002b1d1f4acf6..afcfef838263e3cf9ec1067ce3b92625d4c3056a 100644 (file)
--- a/drivers/base/regmap/regcache.c
+++ b/drivers/base/regmap/regcache.c
@@ -119,7 +119,7 @@ int regcache_init(struct regmap *map)
                if (!tmp_buf)
                        return -ENOMEM;
                map->reg_defaults = tmp_buf;
-       } else {
+       } else if (map->num_reg_defaults_raw) {
                /* Some devices such as PMICs don't have cache defaults,
                 * we cope with this by reading back the HW registers and
                 * crafting the cache defaults by hand.