The issue that I encountered is when doing regmap_update_bits on
a write only register. In regcache path this will not do the right
thing as the register is not readable and driver which is using
regmap_update_bits will never notice that it can not do a update
bits on write only register leading to inconsistent writes and
random hardware behavior.
There seems to be missing checks in regcache_read() which is
now added by moving the orignal check in _regmap_read() before
accessing regcache.
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 5d1729e7f02f ("regmap: Incorporate the regcache core into regmap")
Reported-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>
---
drivers/base/regmap/regmap.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index 297e95be25b3..3ed37a09a8e9 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -2677,6 +2677,9 @@ static int _regmap_read(struct regmap *map, unsigned int reg,
int ret;
void *context = _regmap_map_get_context(map);
+ if (!regmap_readable(map, reg))
+ return -EIO;
+
if (!map->cache_bypass) {
ret = regcache_read(map, reg, val);
if (ret == 0)
@@ -2686,9 +2689,6 @@ static int _regmap_read(struct regmap *map, unsigned int reg,
if (map->cache_only)
return -EBUSY;
- if (!regmap_readable(map, reg))
- return -EIO;
-
ret = map->reg_read(context, reg, val);
if (ret == 0) {
if (regmap_should_log(map))
--
2.21.0
