[RFC][PATCH] regmap: make REGCACHE_NONE maps return error on regcache_sync

[Nariman Poushin <nariman@opensource.wolfsonmicro.com>]

Signed-off-by: Nariman Poushin <nariman@opensource.wolfsonmicro.com>
---
 regcache currently causes a BUG_ON if cache_sync/sync_region is
 called on a map with cache_type REGCACHE_NONE. This is not
 consistent with the behaviour of regcache_read/write which
 currently just return -ENOSYS and only throws a BUG_ON if
 the cache_type is something that _should_ have cache ops,
 but doesn't. Sure your device might not work, it but doesn't
 seem right to panic the kernel. The other option I suppose
 is to change it to a WARN_ON.

 Thanks
 Nariman

 drivers/base/regmap/regcache.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/base/regmap/regcache.c b/drivers/base/regmap/regcache.c
index 7eb7b3b..992aba3 100644
--- a/drivers/base/regmap/regcache.c
+++ b/drivers/base/regmap/regcache.c
@@ -303,6 +303,9 @@ int regcache_sync(struct regmap *map)
 	const char *name;
 	unsigned int bypass;
 
+	if (map->cache_type == REGCACHE_NONE)
+		return -ENODEV;
+
 	BUG_ON(!map->cache_ops);
 
 	map->lock(map->lock_arg);
@@ -371,6 +374,9 @@ int regcache_sync_region(struct regmap *map, unsigned int min,
 	const char *name;
 	unsigned int bypass;
 
+	if (map->cache_type == REGCACHE_NONE)
+		return -ENODEV;
+
 	BUG_ON(!map->cache_ops);
 
 	map->lock(map->lock_arg);
-- 
2.1.4