[ Upstream commit 3b00691cc46a4089368a008b30655a8343411715 ]
24 bit expanders use REG_ADDR_AI in combination with register addressing. This conflicts with regmap which takes this bit as part of the register number, i.e. a second cache entry is defined for accessed with REG_ADDR_AI being set although on the chip it is the same register as with REG_ADDR_AI being cleared.
The problem was introduced by
commit b32cecb46bdc ("gpio: pca953x: Extract the register address mangling to single function")
but only became visible by
commit 8b9f9d4dc511 ("regmap: verify if register is writeable before writing operations")
because before, the regmap size was effectively ignored and pca953x_writeable_register() did know to ignore REG_ADDR_AI. Still, there were two separate cache entries created.
Since the use of REG_ADDR_AI seems to be static we can work around this issue by simply increasing the size of the regmap to cover the "virtual" registers with REG_ADDR_AI being set. This only means that half of the regmap buffer will be unused.
Reported-by: H. Nikolaus Schaller hns@goldelico.com Suggested-by: Linus Walleij linus.walleij@linaro.org Signed-off-by: H. Nikolaus Schaller hns@goldelico.com Signed-off-by: Linus Walleij linus.walleij@linaro.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpio/gpio-pca953x.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/gpio/gpio-pca953x.c b/drivers/gpio/gpio-pca953x.c index 7e76830b3368..b6f10e56dfa0 100644 --- a/drivers/gpio/gpio-pca953x.c +++ b/drivers/gpio/gpio-pca953x.c @@ -306,7 +306,8 @@ static const struct regmap_config pca953x_i2c_regmap = { .volatile_reg = pca953x_volatile_register,
.cache_type = REGCACHE_RBTREE, - .max_register = 0x7f, + /* REVISIT: should be 0x7f but some 24 bit chips use REG_ADDR_AI */ + .max_register = 0xff, };
static u8 pca953x_recalc_addr(struct pca953x_chip *chip, int reg, int off,