regmap: Fix handling of volatile registers for format_write() chips

A previous over-zealous factorisation of code means that we only treat
registers as volatile if they are readable. For most devices this is fine
since normally most registers can be read and volatility implies
readability but for format_write() devices where there is no readback from
the hardware and we use volatility to mean simply uncacheability this means
that we end up treating all registers as cacheble.

A bigger refactoring of the code to clarify this is in order but as a fix
make a minimal change and only check readability when checking volatility
if there is no format_write() operation defined for the device.

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

diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index 78f43fb2fe84647d5e97d5c9f6468cf6c8704187..1cf427bc0d4a8f0ddd9571b69f5dcc14a2167bdb 100644 (file)
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -109,7 +109,7 @@ bool regmap_readable(struct regmap *map, unsigned int reg)
 
 bool regmap_volatile(struct regmap *map, unsigned int reg)
 {
-       if (!regmap_readable(map, reg))
+       if (!map->format.format_write && !regmap_readable(map, reg))
                return false;
 
        if (map->volatile_reg)