[PATCH] regmap: Fix cache defaults initialization from raw cache defaults

[PATCH] regmap: Fix cache defaults initialization from raw cache defaults

[Lars-Peter Clausen]

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>
---
 drivers/base/regmap/regcache.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/base/regmap/regcache.c b/drivers/base/regmap/regcache.c
index 77ce5ff..a10e81c 100644
--- 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;
-- 
1.7.9

Re: [PATCH] regmap: Fix cache defaults initialization from raw cache defaults

[Mark Brown]

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On Wed, Feb 15, 2012 at 10:23:25AM +0100, Lars-Peter Clausen wrote:
> 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").

Applied, thanks.

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